Glycogen branching enzyme: Difference between revisions

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{{Infobox_gene}}
{{enzyme
{{enzyme
| Name = Glycogen branching enzyme
| Name = Glycogen branching enzyme
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{{infobox protein
'''1,4-alpha-glucan-branching enzyme''', also known as '''brancher enzyme''' or '''glycogen-branching enzyme''' is an [[enzyme]] that in humans is encoded by the ''GBE1'' [[gene]].<ref name="entrez">{{cite web | title = Entrez Gene: glucan (1,4-alpha-), branching enzyme 1| url = https://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=retrieve&list_uids=2632| access-date = 2011-08-30}}</ref>
|Name=1,4-alpha-glucan branching enzyme
 
|caption=
'''Glycogen branching enzyme''' is an [[enzyme]] that adds branches to the growing glycogen molecule during the synthesis of [[glycogen]], a storage form of [[glucose]]. More specifically, during glycogen synthesis, a glucose 1-phosphate molecule reacts with uridine triphosphate (UTP) to become UDP-glucose, an activated form of glucose. The activated glucosyl unit of UDP-glucose is then transferred to the hydroxyl group at the C-4 of a terminal residue of glycogen to form an α-1,4-[[glycosidic linkage]], a reaction catalyzed by [[glycogen synthase]]. Importantly, glycogen synthase can only catalyze the synthesis of α-1,4-glycosidic linkages. Since glycogen is a readily mobilized storage form of glucose, the extended glycogen polymer is branched by glycogen branching enzyme to provide glycogen breakdown enzymes, such as [[glycogen phosphorylase]], with a large number of terminal residues for rapid degradation. Branching also importantly increases the solubility and decreases the osmotic strength of glycogen.<ref name=Berg>{{cite book|last=Berg|first=Jeremey | name-list-format = vanc |title=Biochemistry Seventh Edition|year=2012|publisher=W.H. Freeman and Company|pages=627–630}}</ref>
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The protein encoded by this gene is a [[glycogen]] branching [[enzyme]] that [[catalyzes]] the transfer of alpha-1,4-linked [[glucosyl]] units from the outer end of a glycogen chain to an alpha-1,6 position on the same or a neighboring glycogen chain. Branching of the chains is essential to increase the [[solubility]] of the glycogen [[molecule]] and, consequently, in reducing the [[osmotic pressure]] within [[Cell (biology)|cells]]. The highest levels of this enzyme are found in [[liver]] and [[muscle]] cells. [[Mutations]] in this gene are associated with [[glycogen storage disease type IV]] (also known as Andersen's disease).
|HGNCid=4180
|Symbol=GBE1
|AltSymbols=
|EntrezGene=2632
|OMIM=607839
|RefSeq=NM_000158
|UniProt=Q04446
|PDB=
|ECnumber=2.4.1.18
|Chromosome=3
|Arm=p
|Band=12
|LocusSupplementaryData=
}}
'''Glycogen branching enzyme''' is an [[enzyme]] that adds branches to the growing glycogen molecule during the synthesis of [[glycogen]], a storage form of [[glucose]].  
More specifically, during glycogen synthesis, a glucose 1-phosphate molecule reacts with uridine triphosphate (UTP) to become UDP-glucose, an activated form of glucose. The activated glucosyl unit of UDP-glucose is then transferred to the hydroxyl group at the C-4 of a terminal residue of glycogen to form an α-1,4-[[glycosidic linkage]], a reaction catalyzed by [[glycogen synthase]]. Importantly, glycogen synthase can only catalyze the synthesis of α-1,4-glycosidic linkages. Since glycogen is a readily mobilized storage form of glucose, the extended glycogen polymer is branched by glycogen branching enzyme to provide glycogen breakdown enzymes, such as [[glycogen phosphorylase]], with a large number of terminal residues for rapid degradation. Branching also importantly increases the solubility and decreases the osmotic strength of glycogen.<ref name=Berg>{{cite book|last=Berg|first=Jeremey|title=Biochemistry Seventh Edition|year=2012|publisher=W.H. Freeman and Company|pages=627–630}}</ref>


==Nomenclature==
==Nomenclature==
This enzyme belongs to the family of [[transferase]]s, to be specific, those glycosyltransferases that transfer [[hexose]]s ([[hexosyltransferase]]s). The [[List of enzymes|systematic name]] of this enzyme class is '''1,4-alpha-D-glucan:1,4-alpha-D-glucan 6-alpha-D-(1,4-alpha-D-glucano)-transferase'''. Other names in common use include '''branching enzyme''', '''amylo-(1,4→1,6)-transglycosylase''', '''Q-enzyme''', '''alpha-glucan-branching glycosyltransferase''', '''amylose isomerase''', '''enzymatic branching factor''', '''branching glycosyltransferase''', '''enzyme Q''', '''glucosan transglycosylase''', '''1,4-alpha-glucan branching enzyme''', '''plant branching enzyme''', '''alpha-1,4-glucan:alpha-1,4-glucan-6-glycosyltransferase''', and '''starch branching enzyme'''. This enzyme participates in [[starch]] and [[sucrose]] metabolism.
This enzyme belongs to the family of [[transferase]]s, to be specific, those glycosyltransferases that transfer [[hexose]]s ([[hexosyltransferase]]s). The [[List of enzymes|systematic name]] of this enzyme class is 1,4-alpha-D-glucan:1,4-alpha-D-glucan 6-alpha-D-(1,4-alpha-D-glucano)-transferase. Other names in common use include branching enzyme, amylo-(1,4→1,6)-transglycosylase, Q-enzyme, alpha-glucan-branching glycosyltransferase, amylose isomerase, enzymatic branching factor, branching glycosyltransferase, enzyme Q, glucosan transglycosylase, [[1,4-alpha-glucan branching enzyme 1]], plant branching enzyme, alpha-1,4-glucan:alpha-1,4-glucan-6-glycosyltransferase, and starch branching enzyme. This enzyme participates in [[starch]] and [[sucrose]] metabolism.


==Gene==
==Gene==
GBE is encoded by the ''GBE1'' [[gene]].<ref name="entrez">{{cite web | title = Entrez Gene: glucan (1,4-alpha-), branching enzyme 1| url = https://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=retrieve&list_uids=2632| accessdate = 2011-08-30}}</ref><ref name="NCBI GBE1">{{cite web|last=National Center for Biotechnology Information|title=GBE1 glucan (1,4-alpha-), branching enzyme 1 [ Homo sapiens (human) ]|url=https://www.ncbi.nlm.nih.gov/gene?cmd=retrieve&list_uids=2632|publisher=US. National Library of Medicine}}</ref><ref name="OMIM GBE1">{{cite web|last=Online Mendelian Inheritance in Man|title=Glycogen Branching Enzyme; GBE1|url=http://www.omim.org/entry/607839|publisher=Johns Hopkins University}}</ref><ref name="Genetics Home Reference GBE1">{{cite web|last=Genetics Home Reference|title=GBE1|url=http://ghr.nlm.nih.gov/gene/GBE1|publisher=U.S. National Library of Medicine}}</ref>
GBE is encoded by the ''GBE1'' [[gene]].<ref name="entrez" /><ref name="NCBI GBE1">{{cite web|last=National Center for Biotechnology Information|title=GBE1 glucan (1,4-alpha-), branching enzyme 1 [ Homo sapiens (human) ]|url=https://www.ncbi.nlm.nih.gov/gene?cmd=retrieve&list_uids=2632|publisher=US. National Library of Medicine}}</ref><ref name="OMIM GBE1">{{cite web|last=Online Mendelian Inheritance in Man|title=Glycogen Branching Enzyme; GBE1|url=http://www.omim.org/entry/607839|publisher=Johns Hopkins University}}</ref><ref name="Genetics Home Reference GBE1">{{cite web|last=Genetics Home Reference|title=GBE1|url=http://ghr.nlm.nih.gov/gene/GBE1|publisher=U.S. National Library of Medicine}}</ref>


Through [[southern blot]] analysis of DNA derived from human/rodent somatic cell hybrids, GBE1 has been identified as an [[autosomal]] gene located on the short arm of chromosome 3 at position 12.3.<ref name="NCBI GBE1" /><ref name="OMIM GBE1" /><ref name="Genetics Home Reference GBE1" /><ref name="Thon Paper on Gene Location GBE">{{cite journal|last=Thon|first=Vicki |author2=Khalil, Miriam |author3=Cannon, John|title=Isolation of Human Glycogen Branching Enzyme cDNAs by Screening  Complementation in Yeast|journal=The Journal of Biological Chemistry|year=1993|volume=268|pages=7509–7513|url=http://www.jbc.org/content/268/10/7509.full.pdf+html|issue=10}}</ref>  The human GBE gene was also isolated by a function complementation of the Saccharomyces cerevisiae GBE deficiency.<ref name="Thon Paper on Gene Location GBE"/> From the isolated cDNA, the length of the gene was found to be approximately 3 kb.<ref name="Thon Paper on Gene Location GBE"/> Additionally, the coding sequence was found to comprise 2,106 base pairs and encode a 702-amino acid long GBE. The molecular mass of human GBE was calculated to be 80,438 Da.<ref name="Thon Paper on Gene Location GBE"/>
Through [[Southern blot]] analysis of DNA derived from human/rodent somatic cell hybrids, GBE1 has been identified as an [[autosomal]] gene located on the short arm of chromosome 3 at position 12.3.<ref name="NCBI GBE1" /><ref name="OMIM GBE1" /><ref name="Genetics Home Reference GBE1" /><ref name="Thon Paper on Gene Location GBE">{{cite journal | vauthors = Thon VJ, Khalil M, Cannon JF | title = Isolation of human glycogen branching enzyme cDNAs by screening complementation in yeast | journal = The Journal of Biological Chemistry | volume = 268 | issue = 10 | pages = 7509–13 | date = April 1993 | pmid = 8463281 | url = http://www.jbc.org/content/268/10/7509.full.pdf+html }}</ref>  The human GBE gene was also isolated by a function complementation of the Saccharomyces cerevisiae GBE deficiency.<ref name="Thon Paper on Gene Location GBE"/> From the isolated cDNA, the length of the gene was found to be approximately 3 kb.<ref name="Thon Paper on Gene Location GBE"/> Additionally, the coding sequence was found to comprise 2,106 base pairs and encode a 702-amino acid long GBE. The molecular mass of human GBE was calculated to be 80,438 Da.<ref name="Thon Paper on Gene Location GBE"/>


==Structure==
== Structure ==
[[File:E. Coli Glycogen Branching Enzyme.png|thumb|upright=1.35|width=1.35|Structure of glycogen branching enzyme found in E. Coli]]
[[File:E. Coli Glycogen Branching Enzyme.png|thumb|upright=1.35|width=1.35|Structure of glycogen branching enzyme found in E. Coli]]
Glycogen branching enzyme belongs to the [[α-amylase]] family of enzymes, which include α-amylases, pullulanas/isoamylase, cyclodextrin glucanotransferase (CGT), and branching enzyme.<ref name="E. Coli X-ray Crystallographic Structure">{{cite journal|last=Abad|first=Marta |author2=Binderup, Kim |author3=Rios-Steiner, Jorge |author4=Arni, Raghuvir |author5=Preiss, Jack |author6=Geiger, James|title=The X-ray Crystallographic Structure of Escherichia coli Branching Enzyme|journal=The Journal of Biological Chemistry|date=August 23, 2002|volume=277|series=44|pages=42164–42170|url=http://www.jbc.org/content/277/44/42164.full.pdf+html|issue=44|doi=10.1074/jbc.m205746200}}</ref><ref name="Crystal Structure of Mtb">{{cite journal|author = Pal Kuntal|author2 = Kumar, Shiva |author3 = Sharma, Shikha |author4 = Saurabh Kumar |author5 = Alam, Mohammad Suhail |author6 = Xu, H. Eric |author7 = Agrawal, Pushpa |author8 = Swaminathan, Kunchithapadam |title=Crystal Structure of Full-length Mycobacterium tuberculosis H37Rv Glycogen Branching Enzyme INSIGHTS OF N-TERMINAL β-SANDWICH IN SUBSTRATE SPECIFICITY AND ENZYMATIC ACTIVITY|journal=The Journal of Biological Chemistry|date=May 5, 2010|volume=265|pages=20897–20903|url=http://www.jbc.org/content/285/27/20897.long#ref-12}}</ref>  Shown by x-ray crystallography, glycogen branching enzyme has four marginally asymmetric units each that are organized into three domains: an amino-terminal domain, involved in determining the length of the chain transfer, a carboxyl-terminal domain, involved in substrate preference and catalytic capacity, and a central (α/β) barrel catalytic domain.<ref name="E. Coli X-ray Crystallographic Structure" /><ref>{{cite journal|last=Matsuura|first=Yoshiki |author2=Kusunoki, Masami |author3=Harada, Wakako |author4=Kakudo, Masao|title=Structure and Possible Catalytic Residues of Taka-Amylase A|journal=The Journal of Biochemistry|year=1984|volume=95|pages=697–702|url=http://jb.oxfordjournals.org/content/95/3/697.long|issue=3}}</ref><ref>{{cite journal|last=Buisson|first=G|author2=Duee, E |author3=Haser, R |author4=Payan, F |title=Three dimensional structure of porcine pancreatic alpha-amylase at 2.9 A resolution. Role of calcium in structure and activity|journal=The EMBO Journal|date=December 20, 1987|volume=6|pages=3909–3916|pmc=553868 |pmid=3502087 |issue=13}}</ref><ref>{{cite journal|last=Devillers|first=Claire |author2=Piper, Mary |author3=Ballicora, Miguel |author4=Preiss, Jack|title=Characterization of the branching patterns of glycogen branching enzyme truncated on the N-terminus|journal=Archives of Biochemistry and Biophysics|date=October 2003|volume=418|issue=1|pages=34–38|url=http://www.sciencedirect.com/science/article/pii/S0003986103003412|doi=10.1016/S0003-9861(03)00341-2}}</ref> The amino-terminal domain consists of 128 residues arranged in seven β-strands, the carboxyl-terminal domain with 116 residues also organized in seven β-strands, and the (α/β) barrel domain with 372 residues. While the central (α/β) barrel domain is common in members of the α-amylase family, numerous variations exist between the various barrel domains. Additionally, there are striking differences between the loops connecting elements of the secondary structure among these various α-amylase members, especially around the active site. In comparison to the other family members, glycogen binding enzyme has shorter loops, which result in a more open cavity, favorable to the binding of a bulkier substrate such as branched sugar. Through primary structure analysis and the x-ray crystallographic structures of the members of the α-amylase family, seven residue were conserved, Asp335, His340, Arg403, Asp 405, Glu458, His525, and Asp526 (E coli. numbering). These residues are implicated in catalysis and substrate binding.<ref name="E. Coli X-ray Crystallographic Structure" />
Glycogen branching enzyme belongs to the [[α-amylase]] family of enzymes, which include α-amylases, pullulanas/isoamylase, cyclodextrin glucanotransferase (CGT), and branching enzyme.<ref name="E. Coli X-ray Crystallographic Structure">{{cite journal | vauthors = Abad MC, Binderup K, Rios-Steiner J, Arni RK, Preiss J, Geiger JH | title = The X-ray crystallographic structure of Escherichia coli branching enzyme | journal = The Journal of Biological Chemistry | volume = 277 | issue = 44 | pages = 42164–70 | date = November 2002 | pmid = 12196524 | doi = 10.1074/jbc.m205746200 | url = http://www.jbc.org/content/277/44/42164.full.pdf+html | series = 44 }}</ref><ref name="Crystal Structure of Mtb">{{cite journal | vauthors = Pal K, Kumar S, Sharma S, Garg SK, Alam MS, Xu HE, Agrawal P, Swaminathan K | title = Crystal structure of full-length Mycobacterium tuberculosis H37Rv glycogen branching enzyme: insights of N-terminal beta-sandwich in substrate specificity and enzymatic activity | journal = The Journal of Biological Chemistry | volume = 285 | issue = 27 | pages = 20897–903 | date = July 2010 | pmid = 20444687 | doi = 10.1074/jbc.M110.121707 | url = http://www.jbc.org/content/285/27/20897.long#ref-12 | pmc = 2898361 }}</ref>  Shown by x-ray crystallography, glycogen branching enzyme has four marginally asymmetric units each that are organized into three domains: an amino-terminal domain, involved in determining the length of the chain transfer, a carboxyl-terminal domain, involved in substrate preference and catalytic capacity, and a central (α/β) barrel catalytic domain.<ref name="E. Coli X-ray Crystallographic Structure" /><ref>{{cite journal | vauthors = Matsuura Y, Kusunoki M, Harada W, Kakudo M | title = Structure and possible catalytic residues of Taka-amylase A | journal = Journal of Biochemistry | volume = 95 | issue = 3 | pages = 697–702 | date = March 1984 | pmid = 6609921 | url = http://jb.oxfordjournals.org/content/95/3/697.long }}</ref><ref>{{cite journal | vauthors = Buisson G, Duée E, Haser R, Payan F | title = Three dimensional structure of porcine pancreatic alpha-amylase at 2.9 A resolution. Role of calcium in structure and activity | journal = The EMBO Journal | volume = 6 | issue = 13 | pages = 3909–16 | date = December 1987 | pmid = 3502087 | pmc = 553868 }}</ref><ref>{{cite journal | vauthors = Devillers CH, Piper ME, Ballicora MA, Preiss J | title = Characterization of the branching patterns of glycogen branching enzyme truncated on the N-terminus | journal = Archives of Biochemistry and Biophysics | volume = 418 | issue = 1 | pages = 34–8 | date = October 2003 | pmid = 13679080 | doi = 10.1016/S0003-9861(03)00341-2 }}</ref> The amino-terminal domain consists of 128 residues arranged in seven β-strands, the carboxyl-terminal domain with 116 residues also organized in seven β-strands, and the (α/β) barrel domain with 372 residues. While the central (α/β) barrel domain is common in members of the α-amylase family, numerous variations exist between the various barrel domains. Additionally, there are striking differences between the loops connecting elements of the secondary structure among these various α-amylase members, especially around the active site. In comparison to the other family members, glycogen binding enzyme has shorter loops, which result in a more open cavity, favorable to the binding of a bulkier substrate such as branched sugar. Through primary structure analysis and the x-ray crystallographic structures of the members of the α-amylase family, seven residue were conserved, Asp335, His340, Arg403, Asp 405, Glu458, His525, and Asp526 (E coli. numbering). These residues are implicated in catalysis and substrate binding.<ref name="E. Coli X-ray Crystallographic Structure" />


Glycogen binding enzymes in other organisms have also been crystallized and structurally determined, demonstrating both similarity and variation to GBE found in [[Escherichia coli]].<ref>{{cite journal|last=Kuriki|first=Takashi |author2=Stewart, Douglas |author3=Preiss, Jack|title=Construction of Chimeric Enzyme out of Maize Endosperm Branching Enzyme I and II: Activity and Properties|journal=The Journal of Biological Chemistry|year=1997|volume=46|pages=28999–29004|url=http://www.jbc.org/content/272/46/28999.full.pdf+html}}</ref><ref>{{cite journal|author = Palomo, Marta |author2 = Pijning, Tjaard |author3 = Booiman Thijs |author4 = Dobruchowska Justyna |author5 = Van der Vlist Jeroen |author6 = Kralj, Slavko |author7 = Planas, Antoni |author8 = Loos, Katja |author9 = Johannis P. Kamerling |author10 = Bauke W. Dijkstra |author11 = Marc J. E. C |author12 = van der Maarel |author13 = Lubbert Dijkhuizen |author14 = Hans Leemhuis |title=Thermus thermophilus Glycoside Hydrolase Family 57 Branching Enzyme Crystal Structure, Mechanism of Action and Products Formed|journal=The Journal of Biological Chemistry|date=February 4, 2011|volume=286|pages=3520–3530|url=http://www.jbc.org/content/286/5/3520.full.pdf%20(|issue=5|doi=10.1074/jbc.m110.179515 |pmid=21097495 |pmc=3030357}}</ref><ref>{{cite journal|last=Santos|first=Camila |author2=Tonoli, Celisa |author3=Trindade, Daniel |author4=Betzel, Christian |author5=Takata, Hiroki |author6=Kuriki, Takashi |author7=Kanai, Tamotsu |author8=Imanaka, Tadayuki |author9=Arni, Raghuvir |author10=Murakami, Mario|title=Structural basis for branching-enzyme activity of glycoside hydrolase family 57: Structure and stability studies of a novel branching enzyme from the hyperthermophilic archaeon Thermococcus Kodakaraensis KOD1|journal=Proteins|year=2011|volume=79|pages=547–557|url=http://onlinelibrary.wiley.com/store/10.1002/prot.22902/asset/22902_ftp.pdf?v=1&t=hs6qqru7&s=d318f5e0386806512861d50b71a9d46e4339ca79|doi=10.1002/prot.22902 |pmid=21104698}}</ref><ref>{{cite journal|last=Nogushi|first=Junji |author2=Chaen, Kimiko |author3=Vu, Nhuan |author4=Akasaka, Taiki |author5=Shimada, Hiroaki |author6=Nakashima, Takashi |author7=Nishi, Aiko |author8=Satoh, Hikaru |author9=Omori, Toshiro |author10=Kakuta, Yoshimuitsu |author11=Makoto, Kimura|title=Crystal structure of the branching enzyme I (BEI) from Oryza sativa L with implications for catalysis and substrate binding|journal=Glycobiology|date=April 3, 2011|volume=21|pages=1108–1116|url=http://glycob.oxfordjournals.org/content/21/8/1108.long|issue=8|doi=10.1093/glycob/cwr049 |pmid=21493662}}</ref>
Glycogen binding enzymes in other organisms have also been crystallized and structurally determined, demonstrating both similarity and variation to GBE found in [[Escherichia coli]].<ref>{{cite journal | vauthors = Kuriki T, Stewart DC, Preiss J | title = Construction of chimeric enzymes out of maize endosperm branching enzymes I and II: activity and properties | journal = The Journal of Biological Chemistry | volume = 272 | issue = 46 | pages = 28999–9004 | date = November 1997 | pmid = 9360973 | url = http://www.jbc.org/content/272/46/28999.full.pdf+html }}</ref><ref>{{cite journal | vauthors = Palomo M, Pijning T, Booiman T, Dobruchowska JM, van der Vlist J, Kralj S, Planas A, Loos K, Kamerling JP, Dijkstra BW, van der Maarel MJ, Dijkhuizen L, Leemhuis H | title = Thermus thermophilus glycoside hydrolase family 57 branching enzyme: crystal structure, mechanism of action, and products formed | journal = The Journal of Biological Chemistry | volume = 286 | issue = 5 | pages = 3520–30 | date = February 2011 | pmid = 21097495 | pmc = 3030357 | doi = 10.1074/jbc.m110.179515 | url = http://www.jbc.org/content/286/5/3520.full.pdf%20( }}</ref><ref>{{cite journal | vauthors = Santos CR, Tonoli CC, Trindade DM, Betzel C, Takata H, Kuriki T, Kanai T, Imanaka T, Arni RK, Murakami MT | title = Structural basis for branching-enzyme activity of glycoside hydrolase family 57: structure and stability studies of a novel branching enzyme from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 | journal = Proteins | volume = 79 | issue = 2 | pages = 547–57 | date = February 2011 | pmid = 21104698 | doi = 10.1002/prot.22902 | url = http://onlinelibrary.wiley.com/store/10.1002/prot.22902/asset/22902_ftp.pdf?v=1&t=hs6qqru7&s=d318f5e0386806512861d50b71a9d46e4339ca79 }}</ref><ref>{{cite journal | vauthors = Noguchi J, Chaen K, Vu NT, Akasaka T, Shimada H, Nakashima T, Nishi A, Satoh H, Omori T, Kakuta Y, Kimura M | title = Crystal structure of the branching enzyme I (BEI) from Oryza sativa L with implications for catalysis and substrate binding | journal = Glycobiology | volume = 21 | issue = 8 | pages = 1108–16 | date = August 2011 | pmid = 21493662 | doi = 10.1093/glycob/cwr049 }}</ref>


==Function==
== Function ==
[[File:Glycogen Branching Enzyme Scheme.tif|thumb|center|frameless|upright=2.5|width=5|Scheme demonstrating the function of glycogen branching enzyme]]
[[File:Glycogen Branching Enzyme Scheme.tif|thumb|center|frameless|upright=2.5|width=5|Scheme demonstrating the function of glycogen branching enzyme]]
In [[glycogen]], every 10 to 14 [[glucose]] units, a side branch with an additional chain of glucose units occurs. The [[side chain]] attaches at carbon atom 6 of a glucose unit, an α-1,6-glycosidic bond. This connection is catalyzed by a branching enzyme, generally given the name α-glucan branching enzyme. A branching enzyme attaches a string of seven glucose units (with some minor variation to this number) to the carbon at the C-6 position on the glucose unit, forming the α-1,6-glycosidic bond. The specific nature of this enzyme means that this chain of 7 carbons is usually attached to a glucose molecule that is in position three from the [[Non-reducing sugar|non-reducing]] end of another chain. Because the enzyme works with such specificity regarding the number of glucose units transferred and the position to which they are transferred, the enzyme creates the very characteristic, highly branched glycogen molecule.<ref>{{cite book|last=Rose|first=Steven|title=The Chemistry of LIfe|year=1999|publisher=Pelican Books|pages=199–201}}</ref>
In [[glycogen]], every 10 to 14 [[glucose]] units, a side branch with an additional chain of glucose units occurs. The [[side chain]] attaches at carbon atom 6 of a glucose unit, an α-1,6-glycosidic bond. This connection is catalyzed by a branching enzyme, generally given the name α-glucan branching enzyme. A branching enzyme attaches a string of seven glucose units (with some minor variation to this number) to the carbon at the C-6 position on the glucose unit, forming the α-1,6-glycosidic bond. The specific nature of this enzyme means that this chain of 7 carbons is usually attached to a glucose molecule that is in position three from the [[Non-reducing sugar|non-reducing]] end of another chain. Because the enzyme works with such specificity regarding the number of glucose units transferred and the position to which they are transferred, the enzyme creates the very characteristic, highly branched glycogen molecule.<ref>{{cite book|last=Rose|first=Steven | name-list-format = vanc |title=The Chemistry of LIfe|year=1999|publisher=Pelican Books|pages=199–201}}</ref>


==Clinical significance==
==Clinical significance==
Mutations in this gene are associated with [[glycogen storage disease type IV]] (also known as Andersen's disease) in newborns and with [[adult polyglucosan body disease]].<ref name="entrez"/><ref name=OMIM>{{cite web|last1=McKusick|first1=Victor A.|last2=Kniffin|first2=Cassandra L.|title=OMIM Entry 263570 - Polyglucosan body neuropathy, adult form|url=https://omim.org/entry/263570|website=Online Mendelian Inheritance in Man|publisher=Johns Hopkins University|accessdate=7 March 2017|language=en-us|date=May 2, 2016}}</ref>
Mutations in this gene are associated with [[glycogen storage disease type IV]] (also known as Andersen's disease) in newborns and with [[adult polyglucosan body disease]].<ref name="entrez"/><ref name=OMIM>{{cite web|last1=McKusick|first1=Victor A.|last2=Kniffin|first2=Cassandra L. | name-list-format = vanc |title=OMIM Entry 263570 - Polyglucosan body neuropathy, adult form|url=https://omim.org/entry/263570|website=Online Mendelian Inheritance in Man|publisher=Johns Hopkins University|access-date=7 March 2017|language=en-us|date=May 2, 2016}}</ref>
 
Approximately 40 mutations in the GBE1 gene, most resulting in a point mutation in the glycogen branching enzyme, have led to the early childhood disorder, [[glycogen storage disease type IV]] (GSD IV).<ref name="Genetics Home Reference GBE1" />  This disease is characterized by a severe depletion or complete absence of GBE, resulting in the accumulation of abnormally structured glycogen, known as polyglucosan bodies.<ref name="Genetics Home Reference GBE1" />  Glycogen buildup leads to increased osmotic pressure resulting in cellular swelling and death.<ref name="Genetics Home Reference GBE1" />  The tissues most affected by this disease are the liver, heart, and neuromuscular system, areas with the greatest levels of glycogen accumulation.<ref name="Genetics Home Reference GBE1" /><ref>{{cite book|last=Mingyi|first=Chen|title=Glycogen Storages Diseases chapter of Molecular Pathology of Liver Diseases|year=2011|publisher=Springer|pages=677–682|url=https://books.google.com/books?id=pO3SgjPkgCAC&pg=PR13&lpg=PR13&dq=glycogen+storage+diseases+mingyi+chen }}</ref>  Abnormal glycogen buildup in the liver interferes with liver functioning and can result in an enlarged liver and liver disease.<ref name="Genetics Home Reference GBE1" /><ref>{{cite journal | vauthors = Bruno C, van Diggelen OP, Cassandrini D, Gimpelev M, Giuffrè B, Donati MA, Introvini P, Alegria A, Assereto S, Morandi L, Mora M, Tonoli E, Mascelli S, Traverso M, Pasquini E, Bado M, Vilarinho L, van Noort G, Mosca F, DiMauro S, Zara F, Minetti C | author-link20= Salvatore DiMauro| title = Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV) | journal = Neurology | volume = 63 | issue = 6 | pages = 1053–8 | date = September 2004 | pmid = 15452297 | doi = 10.1212/01.wnl.0000138429.11433.0d }}</ref>  In muscles, the inability of cells to efficiently breakdown glycogen due to the severe reduction or absence of branching can lead to muscle weakness and atrophy.<ref name="Genetics Home Reference GBE1" /> 
At least three mutations in the GBE1 gene have been found to cause another disease called adult polyglucosan body disease (APBD).<ref name="Genetics Home Reference GBE1" /><ref name="APBD NCBI">{{cite web|last=Klein|first=Christopher|title=Adult Polyglucosan Body Disease|url=https://www.ncbi.nlm.nih.gov/books/NBK5300/}}</ref>  While in GSD IV GBE activity is undetectable or minimally detectable, APBD is characterized by reduced or even normal GBE activity.<ref name="APBD NCBI"/> In this disease, abnormal glycogen can build up in neurons leading to a spectrum of problems. Specifically, some disease characteristics are [[gait]] difficulties from mixed upper and lower motor neuron involvement sensory loss in lower extremities, and [[neurogenic bladder]], a problem in which a person lacks bladder control due to a brain, spinal cord, or nerve condition.<ref name="APBD NCBI"/><ref>{{cite journal | vauthors = Hussain A, Armistead J, Gushulak L, Kruck C, Pind S, Triggs-Raine B, Natowicz MR | title = The adult polyglucosan body disease mutation GBE1 c.1076A>C occurs at high frequency in persons of Ashkenazi Jewish background | journal = Biochemical and Biophysical Research Communications | volume = 426 | issue = 2 | pages = 286–8 | date = September 2012 | pmid = 22943850 | doi = 10.1016/j.bbrc.2012.08.089 }}</ref>


Approximately 40 mutations in the GBE1 gene, most resulting in a point mutation in the glycogen branching enzyme, have led to the early childhood disorder, [[glycogen storage disease type IV]] (GSD IV).<ref name="Genetics Home Reference GBE1" />  This disease is characterized by a severe depletion or complete absence of GBE, resulting in the accumulation of abnormally structured glycogen, known as polyglucosan bodies.<ref name="Genetics Home Reference GBE1" />  Glycogen buildup leads to increased osmotic pressure resulting in cellular swelling and death.<ref name="Genetics Home Reference GBE1" />  The tissues most affected by this disease are the liver, heart, and neuromuscular system, areas with the greatest levels of glycogen accumulation.<ref name="Genetics Home Reference GBE1" /><ref>{{cite book|last=Mingyi|first=Chen|title=Glycogen Storages Diseases chapter of Molecular Pathology of Liver Diseases|year=2011|publisher=Springer|pages=677–682|url=https://books.google.com/books?id=pO3SgjPkgCAC&pg=PR13&lpg=PR13&dq=glycogen+storage+diseases+mingyi+chen&source=bl&ots=DdRyGdsRTc&sig=RYc5o4XokdgkLe-brTF63jLIYPI&hl=en&sa=X&ei=peIPU9H5JY6CogSou4DQDQ&ved=0CC0Q6AEwAQ#v=onepage&q=glycogen%20storage%20diseases%20mingyi%20chen&f=false}}</ref>  Abnormal glycogen buildup in the liver interferes with liver functioning and can result in an enlarged liver and liver disease.<ref name="Genetics Home Reference GBE1" /><ref>{{cite journal |author = Bruno C. |author2 = Van Diggelen, O.P. |author3 = Cassandrini, D. |author4 = Gimpelev, M. |author5 = Gluffre B. |author6 = Donati  M.A. |author7 =  Introvini, P. |author8 = Alegria, A. |author9 = Assereto, S. |author10 = Morandi, L. |author11 = Mora, M. |author12 = Tonoli, E. |author13 = Mascelli, S. |author14 = Traverso, M. |author15 = Pasquini, E. |author16 = Bado, M. |author17 = Vilarinho, L. |author18 = Van Noort, G. |author19 = Mosca, F. |author20 = DiMauro, S. |author21 = Zara, F. |author22 = Minetti, C.|title=Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV)|journal=Neurology|date=September 28, 2004|volume=63|pages=1053–1058|url=http://www.neurology.org/content/63/6/1053.long|issue=6|doi=10.1212/01.wnl.0000138429.11433.0d|pmid=15452297}}</ref>  In muscles, the inability of cells to efficiently breakdown glycogen due to the severe reduction or absence of branching can lead to muscle weakness and atrophy.<ref name="Genetics Home Reference GBE1" /> 
== Model organisms ==
At least three mutations in the GBE1 gene have been found to cause another disease called adult polyglucosan body disease (APBD).<ref name="Genetics Home Reference GBE1" /><ref name="APBD NCBI">{{cite web|last=Klein|first=Christopher|title=Adult Polyglucosan Body Disease|url=https://www.ncbi.nlm.nih.gov/books/NBK5300/}}</ref>  While in GSD IV GBE activity is undetectable or minimally detectable, APBD is characterized by reduced or even normal GBE activity.<ref name="APBD NCBI"/> In this disease, abnormal glycogen can build up in neurons leading to a spectrum of problems. Specifically, some disease characteristics are [[gait]] difficulties from mixed upper and lower motor neuron involvement sensory loss in lower extremities, and [[neurogenic bladder]], a problem in which a person lacks bladder control due to a brain, spinal cord, or nerve condition.<ref name="APBD NCBI"/><ref>{{cite journal|last=Hussain|first=Abrar |author2=Armistead, Joy |author3=Gushulak, Lara |author4=Kruck, Christa |author5=Pind, Steven |author6=Triggs-Raine, Barbara |author7=Natowicz, Marvin|title=The adult polyglucosan body disease mutation GBE1 c.1076A>C occurs at high frequency in persons of Ashkenazi Jewish background|journal=Biochemical and Biophysical Research Communications|date=September 2002|volume=426|pages=286–288|url=http://www.sciencedirect.com/science/article/pii/S0006291X12016543|doi=10.1016/j.bbrc.2012.08.089 |pmid=22943850}}</ref>


==Model organisms==
{| class="wikitable sortable collapsible collapsed" border="1" cellpadding="2" style="float: right;" |
{| class="wikitable sortable collapsible collapsed" border="1" cellpadding="2" style="float: right;" |
|+ ''Gbe1'' knockout mouse phenotype
|+ ''Gbe1'' knockout mouse phenotype
Line 116: Line 102:
| colspan=2; style="text-align: center;" | All tests and analysis from<ref name="mgp_reference">{{cite journal | doi = 10.1111/j.1755-3768.2010.4142.x | title = The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice | year = 2010 | author = Gerdin AK | journal = Acta Ophthalmologica | volume = 88 | pages =  925–7 }}</ref><ref>[http://www.sanger.ac.uk/mouseportal/ Mouse Resources Portal], Wellcome Trust Sanger Institute.</ref>
| colspan=2; style="text-align: center;" | All tests and analysis from<ref name="mgp_reference">{{cite journal | doi = 10.1111/j.1755-3768.2010.4142.x | title = The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice | year = 2010 | author = Gerdin AK | journal = Acta Ophthalmologica | volume = 88 | pages =  925–7 }}</ref><ref>[http://www.sanger.ac.uk/mouseportal/ Mouse Resources Portal], Wellcome Trust Sanger Institute.</ref>
|}
|}
[[Model organism]]s have been used in the study of GBE1 function. A conditional [[knockout mouse]] line, called ''Gbe1<sup>tm1a(KOMP)Wtsi</sup>''<ref name="allele_ref">{{cite web |url=http://www.knockoutmouse.org/martsearch/search?query=Gbe1 |title=International Knockout Mouse Consortium}}</ref><ref name="mgi_allele_ref">{{cite web |url=http://www.informatics.jax.org/searchtool/Search.do?query=MGI:4364560 |title=Mouse Genome Informatics}}</ref> was generated as part of the [[International Knockout Mouse Consortium]] program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.<ref name="pmid21677750">{{cite journal | vauthors = Skarnes WC, Rosen B, West AP, Koutsourakis M, Bushell W, Iyer V, Mujica AO, Thomas M, Harrow J, Cox T, Jackson D, Severin J, Biggs P, Fu J, Nefedov M, de Jong PJ, Stewart AF, Bradley A | title = A conditional knockout resource for the genome-wide study of mouse gene function | journal = Nature | volume = 474 | issue = 7351 | pages = 337–42 | date = Jun 2011 | pmid = 21677750 | pmc = 3572410 | doi = 10.1038/nature10163 }}</ref><ref name="mouse_library">{{cite journal | vauthors = Dolgin E | title = Mouse library set to be knockout | journal = Nature | volume = 474 | issue = 7351 | pages = 262–3 | date = Jun 2011 | pmid = 21677718 | doi = 10.1038/474262a }}</ref><ref name="mouse_for_all_reasons">{{cite journal | vauthors = Collins FS, Rossant J, Wurst W | title = A mouse for all reasons | journal = Cell | volume = 128 | issue = 1 | pages = 9–13 | date = Jan 2007 | pmid = 17218247 | doi = 10.1016/j.cell.2006.12.018 }}</ref>
[[Model organism]]s have been used in the study of GBE1 function. A conditional [[knockout mouse]] line, called ''Gbe1<sup>tm1a(KOMP)Wtsi</sup>''<ref name="allele_ref">{{cite web |url=http://www.knockoutmouse.org/martsearch/search?query=Gbe1 |title=International Knockout Mouse Consortium}}</ref><ref name="mgi_allele_ref">{{cite web |url=http://www.informatics.jax.org/searchtool/Search.do?query=MGI:4364560 |title=Mouse Genome Informatics}}</ref> was generated as part of the [[International Knockout Mouse Consortium]] program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.<ref name="pmid21677750">{{cite journal | vauthors = Skarnes WC, Rosen B, West AP, Koutsourakis M, Bushell W, Iyer V, Mujica AO, Thomas M, Harrow J, Cox T, Jackson D, Severin J, Biggs P, Fu J, Nefedov M, de Jong PJ, Stewart AF, Bradley A | title = A conditional knockout resource for the genome-wide study of mouse gene function | journal = Nature | volume = 474 | issue = 7351 | pages = 337–42 | date = June 2011 | pmid = 21677750 | pmc = 3572410 | doi = 10.1038/nature10163 }}</ref><ref name="mouse_library">{{cite journal | vauthors = Dolgin E | title = Mouse library set to be knockout | journal = Nature | volume = 474 | issue = 7351 | pages = 262–3 | date = June 2011 | pmid = 21677718 | doi = 10.1038/474262a }}</ref><ref name="mouse_for_all_reasons">{{cite journal | vauthors = Collins FS, Rossant J, Wurst W | title = A mouse for all reasons | journal = Cell | volume = 128 | issue = 1 | pages = 9–13 | date = January 2007 | pmid = 17218247 | doi = 10.1016/j.cell.2006.12.018 }}</ref>


Male and female animals underwent a standardized [[phenotypic screen]] to determine the effects of deletion.<ref name="mgp_reference" /><ref name="pmid21722353">{{cite journal | vauthors = van der Weyden L, White JK, Adams DJ, Logan DW | title = The mouse genetics toolkit: revealing function and mechanism | journal = Genome Biology | volume = 12 | issue = 6 | pages = 224 | year = 2011 | pmid = 21722353 | pmc = 3218837 | doi = 10.1186/gb-2011-12-6-224 }}</ref> Twenty six tests were carried out on [[mutant]] mice and two significant abnormalities were observed.<ref name="mgp_reference" />  No [[homozygous]] [[mutant]] embryos were identified during gestation, and therefore none survived until [[weaning]]. The remaining tests were carried out on [[heterozygous]] mutant adult mice; no additional significant abnormalities were observed in these animals.<ref name="mgp_reference" />
Male and female animals underwent a standardized [[phenotypic screen]] to determine the effects of deletion.<ref name="mgp_reference" /><ref name="pmid21722353">{{cite journal | vauthors = van der Weyden L, White JK, Adams DJ, Logan DW | title = The mouse genetics toolkit: revealing function and mechanism | journal = Genome Biology | volume = 12 | issue = 6 | pages = 224 | date = June 2011 | pmid = 21722353 | pmc = 3218837 | doi = 10.1186/gb-2011-12-6-224 }}</ref> Twenty six tests were carried out on [[mutant]] mice and two significant abnormalities were observed.<ref name="mgp_reference" />  No [[homozygous]] [[mutant]] embryos were identified during gestation, and therefore none survived until [[weaning]]. The remaining tests were carried out on [[heterozygous]] mutant adult mice; no additional significant abnormalities were observed in these animals.<ref name="mgp_reference" />


==References==
== References ==
{{Reflist}}
{{Reflist|32em}}


== Further reading ==
== Further reading ==
{{refbegin|32em}}
* {{cite journal |vauthors=Barker SA, Bourne E, Peat S | location = Lond. | title = The enzymic synthesis and degradation of starch. Part IV. The purification and storage of the Q-enzyme of the potato | journal = J. Chem. | volume = Soc. | pages = 1705&ndash;1711 | doi=10.1039/jr9490001705}}
* {{cite journal |vauthors=Barker SA, Bourne E, Peat S | location = Lond. | title = The enzymic synthesis and degradation of starch. Part IV. The purification and storage of the Q-enzyme of the potato | journal = J. Chem. | volume = Soc. | pages = 1705&ndash;1711 | doi=10.1039/jr9490001705}}
* {{cite journal |vauthors=Baum H, Gilbert GA| year = 1953 | title = A simple method for the preparation of crystalline potato phosphorylase and Q-enzyme | journal = Nature | volume = 171 | pages = 983&ndash;984 | doi = 10.1038/171983a0 | pmid=13063502 | issue=4361}}
* {{cite journal | vauthors = Baum H, Gilbert GA | title = A simple method for the preparation of crystalline potato phosphorylase and Q-enzyme | journal = Nature | volume = 171 | issue = 4361 | pages = 983–4 | date = May 1953 | pmid = 13063502 | doi = 10.1038/171983a0 }}
* {{cite journal | author = Hehre EJ | year = 1951 | title = Advances in Enzymology and Related Areas of Molecular Biology; chapter: Enzymic Synthesis of Polysaccharides: a Biological type of Polymerization | journal = Adv. Enzymol. Relat. Subj. Biochem. | volume = 11 | pages = 297&ndash;337 | doi = 10.1002/9780470122563.ch6 | series = Advances in Enzymology - and Related Areas of Molecular Biology | isbn = 978-0-470-12256-3 }}
* {{cite journal | vauthors = Hehre EJ | year = 1951 | title = Advances in Enzymology and Related Areas of Molecular Biology; chapter: Enzymic Synthesis of Polysaccharides: a Biological type of Polymerization | journal = Adv. Enzymol. Relat. Subj. Biochem. | volume = 11 | pages = 297&ndash;337 | doi = 10.1002/9780470122563.ch6 | series = Advances in Enzymology - and Related Areas of Molecular Biology | isbn = 978-0-470-12256-3 }}
* {{cite journal | author = Handelsman DJ | year = 2006 | title = Follicle-stimulating hormone increases primordial follicle reserve in mature female hypogonadal mice | journal = J. Endocrinol. | volume = 188 | pages = 549&ndash;57  | pmid = 16522734 | doi = 10.1677/joe.1.06614 | last2 = Wang | first2 = Y | last3 = Jimenez | first3 = M | last4 = Marshan | first4 = B | last5 = Spaliviero | first5 = J | last6 = Illingworth | first6 = P | last7 = Handelsman | first7 = DJ | issue = 3 }}
* {{cite journal | vauthors = Allan CM, Wang Y, Jimenez M, Marshan B, Spaliviero J, Illingworth P, Handelsman DJ | title = Follicle-stimulating hormone increases primordial follicle reserve in mature female hypogonadal mice | journal = The Journal of Endocrinology | volume = 188 | issue = 3 | pages = 549–57 | date = March 2006 | pmid = 16522734 | doi = 10.1677/joe.1.06614 }}
* {{cite journal | vauthors = Stelzl U, Worm U, Lalowski M, Haenig C, Brembeck FH, Goehler H, Stroedicke M, Zenkner M, Schoenherr A, Koeppen S, Timm J, Mintzlaff S, Abraham C, Bock N, Kietzmann S, Goedde A, Toksöz E, Droege A, Krobitsch S, Korn B, Birchmeier W, Lehrach H, Wanker EE | title = A human protein-protein interaction network: a resource for annotating the proteome | journal = Cell | volume = 122 | issue = 6 | pages = 957–68 | date = Sep 2005 | pmid = 16169070 | doi = 10.1016/j.cell.2005.08.029 }}
* {{cite journal | vauthors = Stelzl U, Worm U, Lalowski M, Haenig C, Brembeck FH, Goehler H, Stroedicke M, Zenkner M, Schoenherr A, Koeppen S, Timm J, Mintzlaff S, Abraham C, Bock N, Kietzmann S, Goedde A, Toksöz E, Droege A, Krobitsch S, Korn B, Birchmeier W, Lehrach H, Wanker EE | title = A human protein-protein interaction network: a resource for annotating the proteome | journal = Cell | volume = 122 | issue = 6 | pages = 957–68 | date = September 2005 | pmid = 16169070 | doi = 10.1016/j.cell.2005.08.029 }}
* {{cite journal | vauthors = Massa R, Bruno C, Martorana A, de Stefano N, van Diggelen OP, Federico A | title = Adult polyglucosan body disease: proton magnetic resonance spectroscopy of the brain and novel mutation in the GBE1 gene | journal = Muscle & Nerve | volume = 37 | issue = 4 | pages = 530–6 | date = Apr 2008 | pmid = 17994551 | doi = 10.1002/mus.20916 }}
* {{cite journal | vauthors = Massa R, Bruno C, Martorana A, de Stefano N, van Diggelen OP, Federico A | title = Adult polyglucosan body disease: proton magnetic resonance spectroscopy of the brain and novel mutation in the GBE1 gene | journal = Muscle & Nerve | volume = 37 | issue = 4 | pages = 530–6 | date = April 2008 | pmid = 17994551 | doi = 10.1002/mus.20916 }}
* {{cite journal | vauthors = Rose JE, Behm FM, Drgon T, Johnson C, Uhl GR | title = Personalized smoking cessation: interactions between nicotine dose, dependence and quit-success genotype score | journal = Molecular Medicine | volume = 16 | issue = 7–8 | pages = 247–53 | pmid = 20379614 | pmc = 2896464 | doi = 10.2119/molmed.2009.00159 }}
* {{cite journal | vauthors = Rose JE, Behm FM, Drgon T, Johnson C, Uhl GR | title = Personalized smoking cessation: interactions between nicotine dose, dependence and quit-success genotype score | journal = Molecular Medicine | volume = 16 | issue = 7-8 | pages = 247–53 | pmid = 20379614 | pmc = 2896464 | doi = 10.2119/molmed.2009.00159 }}
* {{cite journal | vauthors = Hannula-Jouppi K, Kaminen-Ahola N, Taipale M, Eklund R, Nopola-Hemmi J, Kääriäinen H, Kere J | title = The axon guidance receptor gene ROBO1 is a candidate gene for developmental dyslexia | journal = PLoS Genetics | volume = 1 | issue = 4 | pages = e50 | date = Oct 2005 | pmid = 16254601 | pmc = 1270007 | doi = 10.1371/journal.pgen.0010050 }}
* {{cite journal | vauthors = Hannula-Jouppi K, Kaminen-Ahola N, Taipale M, Eklund R, Nopola-Hemmi J, Kääriäinen H, Kere J | title = The axon guidance receptor gene ROBO1 is a candidate gene for developmental dyslexia | journal = PLoS Genetics | volume = 1 | issue = 4 | pages = e50 | date = October 2005 | pmid = 16254601 | pmc = 1270007 | doi = 10.1371/journal.pgen.0010050 }}
* {{cite journal | vauthors = Konstantinidou AE, Anninos H, Dertinger S, Nonni A, Petersen M, Karadimas C, Havaki S, Marinos E, Akman HO, DiMauro S, Patsouris E | title = Placental involvement in glycogen storage disease type IV | journal = Placenta | volume = 29 | issue = 4 | pages = 378–81 | date = Apr 2008 | pmid = 18289670 | doi = 10.1016/j.placenta.2008.01.005 }}
* {{cite journal | vauthors = Konstantinidou AE, Anninos H, Dertinger S, Nonni A, Petersen M, Karadimas C, Havaki S, Marinos E, Akman HO, DiMauro S, Patsouris E | title = Placental involvement in glycogen storage disease type IV | journal = Placenta | volume = 29 | issue = 4 | pages = 378–81 | date = April 2008 | pmid = 18289670 | doi = 10.1016/j.placenta.2008.01.005 }}
* {{cite journal | vauthors = Melén E, Himes BE, Brehm JM, Boutaoui N, Klanderman BJ, Sylvia JS, Lasky-Su J | title = Analyses of shared genetic factors between asthma and obesity in children | journal = The Journal of Allergy and Clinical Immunology | volume = 126 | issue = 3 | pages = 631–7.e1-8 | date = Sep 2010 | pmid = 20816195 | pmc = 2941152 | doi = 10.1016/j.jaci.2010.06.030 }}
* {{cite journal | vauthors = Melén E, Himes BE, Brehm JM, Boutaoui N, Klanderman BJ, Sylvia JS, Lasky-Su J | title = Analyses of shared genetic factors between asthma and obesity in children | journal = The Journal of Allergy and Clinical Immunology | volume = 126 | issue = 3 | pages = 631–7.e1-8 | date = September 2010 | pmid = 20816195 | pmc = 2941152 | doi = 10.1016/j.jaci.2010.06.030 }}
* {{cite journal | vauthors = Bruno C, van Diggelen OP, Cassandrini D, Gimpelev M, Giuffrè B, Donati MA, Introvini P, Alegria A, Assereto S, Morandi L, Mora M, Tonoli E, Mascelli S, Traverso M, Pasquini E, Bado M, Vilarinho L, van Noort G, Mosca F, DiMauro S, Zara F, Minetti C | title = Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV) | journal = Neurology | volume = 63 | issue = 6 | pages = 1053–8 | date = Sep 2004 | pmid = 15452297 | doi = 10.1212/01.wnl.0000138429.11433.0d }}
* {{cite journal | vauthors = Bruno C, van Diggelen OP, Cassandrini D, Gimpelev M, Giuffrè B, Donati MA, Introvini P, Alegria A, Assereto S, Morandi L, Mora M, Tonoli E, Mascelli S, Traverso M, Pasquini E, Bado M, Vilarinho L, van Noort G, Mosca F, DiMauro S, Zara F, Minetti C | title = Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV) | journal = Neurology | volume = 63 | issue = 6 | pages = 1053–8 | date = September 2004 | pmid = 15452297 | doi = 10.1212/01.wnl.0000138429.11433.0d }}
* {{cite journal | vauthors = Ziemssen F, Sindern E, Schröder JM, Shin YS, Zange J, Kilimann MW, Malin JP, Vorgerd M | title = Novel missense mutations in the glycogen-branching enzyme gene in adult polyglucosan body disease | journal = Annals of Neurology | volume = 47 | issue = 4 | pages = 536–40 | date = Apr 2000 | pmid = 10762170 | doi = 10.1002/1531-8249(200004)47:4<536::AID-ANA22>3.0.CO;2-K }}
* {{cite journal | vauthors = Ziemssen F, Sindern E, Schröder JM, Shin YS, Zange J, Kilimann MW, Malin JP, Vorgerd M | title = Novel missense mutations in the glycogen-branching enzyme gene in adult polyglucosan body disease | journal = Annals of Neurology | volume = 47 | issue = 4 | pages = 536–40 | date = April 2000 | pmid = 10762170 | doi = 10.1002/1531-8249(200004)47:4<536::AID-ANA22>3.0.CO;2-K }}
* {{cite journal | vauthors = McCarthy JJ, Meyer J, Moliterno DJ, Newby LK, Rogers WJ, Topol EJ | title = Evidence for substantial effect modification by gender in a large-scale genetic association study of the metabolic syndrome among coronary heart disease patients | journal = Human Genetics | volume = 114 | issue = 1 | pages = 87–98 | date = Dec 2003 | pmid = 14557872 | doi = 10.1007/s00439-003-1026-1 }}
* {{cite journal | vauthors = McCarthy JJ, Meyer J, Moliterno DJ, Newby LK, Rogers WJ, Topol EJ | title = Evidence for substantial effect modification by gender in a large-scale genetic association study of the metabolic syndrome among coronary heart disease patients | journal = Human Genetics | volume = 114 | issue = 1 | pages = 87–98 | date = December 2003 | pmid = 14557872 | doi = 10.1007/s00439-003-1026-1 }}
* {{cite journal | vauthors = Tay SK, Akman HO, Chung WK, Pike MG, Muntoni F, Hays AP, Shanske S, Valberg SJ, Mickelson JR, Tanji K, DiMauro S | title = Fatal infantile neuromuscular presentation of glycogen storage disease type IV | journal = Neuromuscular Disorders | volume = 14 | issue = 4 | pages = 253–60 | date = Apr 2004 | pmid = 15019703 | doi = 10.1016/j.nmd.2003.12.006 }}
* {{cite journal | vauthors = Tay SK, Akman HO, Chung WK, Pike MG, Muntoni F, Hays AP, Shanske S, Valberg SJ, Mickelson JR, Tanji K, DiMauro S | title = Fatal infantile neuromuscular presentation of glycogen storage disease type IV | journal = Neuromuscular Disorders | volume = 14 | issue = 4 | pages = 253–60 | date = April 2004 | pmid = 15019703 | doi = 10.1016/j.nmd.2003.12.006 }}
* {{cite journal | vauthors = Pescador N, Villar D, Cifuentes D, Garcia-Rocha M, Ortiz-Barahona A, Vazquez S, Ordoñez A, Cuevas Y, Saez-Morales D, Garcia-Bermejo ML, Landazuri MO, Guinovart J, del Peso L | title = Hypoxia promotes glycogen accumulation through hypoxia inducible factor (HIF)-mediated induction of glycogen synthase 1 | journal = PLOS ONE | volume = 5 | issue = 3 | pages = e9644 | year = 2010 | pmid = 20300197 | pmc = 2837373 | doi = 10.1371/journal.pone.0009644 }}
* {{cite journal | vauthors = Pescador N, Villar D, Cifuentes D, Garcia-Rocha M, Ortiz-Barahona A, Vazquez S, Ordoñez A, Cuevas Y, Saez-Morales D, Garcia-Bermejo ML, Landazuri MO, Guinovart J, del Peso L | title = Hypoxia promotes glycogen accumulation through hypoxia inducible factor (HIF)-mediated induction of glycogen synthase 1 | journal = PLOS One | volume = 5 | issue = 3 | pages = e9644 | date = March 2010 | pmid = 20300197 | pmc = 2837373 | doi = 10.1371/journal.pone.0009644 }}
* {{cite journal | vauthors = Bruno C, Cassandrini D, Assereto S, Akman HO, Minetti C, Di Mauro S | title = Neuromuscular forms of glycogen branching enzyme deficiency | journal = Acta Myologica | volume = 26 | issue = 1 | pages = 75–8 | date = Jul 2007 | pmid = 17915577 | pmc = 2949312 | doi =  }}
* {{cite journal | vauthors = Bruno C, Cassandrini D, Assereto S, Akman HO, Minetti C, Di Mauro S | title = Neuromuscular forms of glycogen branching enzyme deficiency | journal = Acta Myologica | volume = 26 | issue = 1 | pages = 75–8 | date = July 2007 | pmid = 17915577 | pmc = 2949312 | doi =  }}
* {{cite journal | vauthors = Flachsbart F, Franke A, Kleindorp R, Caliebe A, Blanché H, Schreiber S, Nebel A | title = Investigation of genetic susceptibility factors for human longevity - a targeted nonsynonymous SNP study | journal = Mutation Research | volume = 694 | issue = 1–2 | pages = 13–9 | date = Dec 2010 | pmid = 20800603 | doi = 10.1016/j.mrfmmm.2010.08.006 }}
* {{cite journal | vauthors = Flachsbart F, Franke A, Kleindorp R, Caliebe A, Blanché H, Schreiber S, Nebel A | title = Investigation of genetic susceptibility factors for human longevity - a targeted nonsynonymous SNP study | journal = Mutation Research | volume = 694 | issue = 1-2 | pages = 13–9 | date = December 2010 | pmid = 20800603 | doi = 10.1016/j.mrfmmm.2010.08.006 }}
* {{cite journal | vauthors = Rush J, Moritz A, Lee KA, Guo A, Goss VL, Spek EJ, Zhang H, Zha XM, Polakiewicz RD, Comb MJ | title = Immunoaffinity profiling of tyrosine phosphorylation in cancer cells | journal = Nature Biotechnology | volume = 23 | issue = 1 | pages = 94–101 | date = Jan 2005 | pmid = 15592455 | doi = 10.1038/nbt1046 }}
* {{cite journal | vauthors = Rush J, Moritz A, Lee KA, Guo A, Goss VL, Spek EJ, Zhang H, Zha XM, Polakiewicz RD, Comb MJ | title = Immunoaffinity profiling of tyrosine phosphorylation in cancer cells | journal = Nature Biotechnology | volume = 23 | issue = 1 | pages = 94–101 | date = January 2005 | pmid = 15592455 | doi = 10.1038/nbt1046 }}
* {{cite journal | vauthors = Bailey SD, Xie C, Do R, Montpetit A, Diaz R, Mohan V, Keavney B, Yusuf S, Gerstein HC, Engert JC, Anand S | title = Variation at the NFATC2 locus increases the risk of thiazolidinedione-induced edema in the Diabetes REduction Assessment with ramipril and rosiglitazone Medication (DREAM) study | journal = Diabetes Care | volume = 33 | issue = 10 | pages = 2250–3 | date = Oct 2010 | pmid = 20628086 | pmc = 2945168 | doi = 10.2337/dc10-0452 }}
* {{cite journal | vauthors = Bailey SD, Xie C, Do R, Montpetit A, Diaz R, Mohan V, Keavney B, Yusuf S, Gerstein HC, Engert JC, Anand S | title = Variation at the NFATC2 locus increases the risk of thiazolidinedione-induced edema in the Diabetes REduction Assessment with ramipril and rosiglitazone Medication (DREAM) study | journal = Diabetes Care | volume = 33 | issue = 10 | pages = 2250–3 | date = October 2010 | pmid = 20628086 | pmc = 2945168 | doi = 10.2337/dc10-0452 }}
{{refend}}


==External links==
==External links==
* [https://www.ncbi.nlm.nih.gov/books/NBK5300/  GeneReviews/NCBI/NIH/UW entry on Adult Polyglucosan Body Disease]
{{Commonscat}}
* [https://www.ncbi.nlm.nih.gov/omim/232500,263570,607839,263570,607839  OMIM entries on Adult Polyglucosan Body Disease]
*[https://www.ncbi.nlm.nih.gov/books/NBK5300/  GeneReviews/NCBI/NIH/UW entry on Adult Polyglucosan Body Disease]
*[https://www.ncbi.nlm.nih.gov/omim/232500,263570,607839,263570,607839  OMIM entries on Adult Polyglucosan Body Disease]


{{Glycogenesis and glycogenolysis}}
{{Glycogenesis and glycogenolysis}}
{{Glycosyltransferases}}
{{Glycosyltransferases}}
{{Enzymes}}
{{Enzymes}}
{{Portal bar|Molecular and Cellular Biology|border=no}}
{{Portal bar|Molecular and Cellular Biology|Metabolism|border=no}}


[[Category:EC 2.4.1]]
[[Category:EC 2.4.1]]

Latest revision as of 21:52, 31 October 2018

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Identifiers
Aliases
External IDsGeneCards: [1]
Orthologs
SpeciesHumanMouse
Entrez

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Ensembl

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UniProt

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RefSeq (mRNA)

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Glycogen branching enzyme
Identifiers
EC number2.4.1.18
CAS number9001-97-2
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO

1,4-alpha-glucan-branching enzyme, also known as brancher enzyme or glycogen-branching enzyme is an enzyme that in humans is encoded by the GBE1 gene.[1]

Glycogen branching enzyme is an enzyme that adds branches to the growing glycogen molecule during the synthesis of glycogen, a storage form of glucose. More specifically, during glycogen synthesis, a glucose 1-phosphate molecule reacts with uridine triphosphate (UTP) to become UDP-glucose, an activated form of glucose. The activated glucosyl unit of UDP-glucose is then transferred to the hydroxyl group at the C-4 of a terminal residue of glycogen to form an α-1,4-glycosidic linkage, a reaction catalyzed by glycogen synthase. Importantly, glycogen synthase can only catalyze the synthesis of α-1,4-glycosidic linkages. Since glycogen is a readily mobilized storage form of glucose, the extended glycogen polymer is branched by glycogen branching enzyme to provide glycogen breakdown enzymes, such as glycogen phosphorylase, with a large number of terminal residues for rapid degradation. Branching also importantly increases the solubility and decreases the osmotic strength of glycogen.[2]

The protein encoded by this gene is a glycogen branching enzyme that catalyzes the transfer of alpha-1,4-linked glucosyl units from the outer end of a glycogen chain to an alpha-1,6 position on the same or a neighboring glycogen chain. Branching of the chains is essential to increase the solubility of the glycogen molecule and, consequently, in reducing the osmotic pressure within cells. The highest levels of this enzyme are found in liver and muscle cells. Mutations in this gene are associated with glycogen storage disease type IV (also known as Andersen's disease).

Nomenclature

This enzyme belongs to the family of transferases, to be specific, those glycosyltransferases that transfer hexoses (hexosyltransferases). The systematic name of this enzyme class is 1,4-alpha-D-glucan:1,4-alpha-D-glucan 6-alpha-D-(1,4-alpha-D-glucano)-transferase. Other names in common use include branching enzyme, amylo-(1,4→1,6)-transglycosylase, Q-enzyme, alpha-glucan-branching glycosyltransferase, amylose isomerase, enzymatic branching factor, branching glycosyltransferase, enzyme Q, glucosan transglycosylase, 1,4-alpha-glucan branching enzyme 1, plant branching enzyme, alpha-1,4-glucan:alpha-1,4-glucan-6-glycosyltransferase, and starch branching enzyme. This enzyme participates in starch and sucrose metabolism.

Gene

GBE is encoded by the GBE1 gene.[1][3][4][5]

Through Southern blot analysis of DNA derived from human/rodent somatic cell hybrids, GBE1 has been identified as an autosomal gene located on the short arm of chromosome 3 at position 12.3.[3][4][5][6] The human GBE gene was also isolated by a function complementation of the Saccharomyces cerevisiae GBE deficiency.[6] From the isolated cDNA, the length of the gene was found to be approximately 3 kb.[6] Additionally, the coding sequence was found to comprise 2,106 base pairs and encode a 702-amino acid long GBE. The molecular mass of human GBE was calculated to be 80,438 Da.[6]

Structure

File:E. Coli Glycogen Branching Enzyme.png
Structure of glycogen branching enzyme found in E. Coli

Glycogen branching enzyme belongs to the α-amylase family of enzymes, which include α-amylases, pullulanas/isoamylase, cyclodextrin glucanotransferase (CGT), and branching enzyme.[7][8] Shown by x-ray crystallography, glycogen branching enzyme has four marginally asymmetric units each that are organized into three domains: an amino-terminal domain, involved in determining the length of the chain transfer, a carboxyl-terminal domain, involved in substrate preference and catalytic capacity, and a central (α/β) barrel catalytic domain.[7][9][10][11] The amino-terminal domain consists of 128 residues arranged in seven β-strands, the carboxyl-terminal domain with 116 residues also organized in seven β-strands, and the (α/β) barrel domain with 372 residues. While the central (α/β) barrel domain is common in members of the α-amylase family, numerous variations exist between the various barrel domains. Additionally, there are striking differences between the loops connecting elements of the secondary structure among these various α-amylase members, especially around the active site. In comparison to the other family members, glycogen binding enzyme has shorter loops, which result in a more open cavity, favorable to the binding of a bulkier substrate such as branched sugar. Through primary structure analysis and the x-ray crystallographic structures of the members of the α-amylase family, seven residue were conserved, Asp335, His340, Arg403, Asp 405, Glu458, His525, and Asp526 (E coli. numbering). These residues are implicated in catalysis and substrate binding.[7]

Glycogen binding enzymes in other organisms have also been crystallized and structurally determined, demonstrating both similarity and variation to GBE found in Escherichia coli.[12][13][14][15]

Function

File:Glycogen Branching Enzyme Scheme.tif
Scheme demonstrating the function of glycogen branching enzyme

In glycogen, every 10 to 14 glucose units, a side branch with an additional chain of glucose units occurs. The side chain attaches at carbon atom 6 of a glucose unit, an α-1,6-glycosidic bond. This connection is catalyzed by a branching enzyme, generally given the name α-glucan branching enzyme. A branching enzyme attaches a string of seven glucose units (with some minor variation to this number) to the carbon at the C-6 position on the glucose unit, forming the α-1,6-glycosidic bond. The specific nature of this enzyme means that this chain of 7 carbons is usually attached to a glucose molecule that is in position three from the non-reducing end of another chain. Because the enzyme works with such specificity regarding the number of glucose units transferred and the position to which they are transferred, the enzyme creates the very characteristic, highly branched glycogen molecule.[16]

Clinical significance

Mutations in this gene are associated with glycogen storage disease type IV (also known as Andersen's disease) in newborns and with adult polyglucosan body disease.[1][17]

Approximately 40 mutations in the GBE1 gene, most resulting in a point mutation in the glycogen branching enzyme, have led to the early childhood disorder, glycogen storage disease type IV (GSD IV).[5] This disease is characterized by a severe depletion or complete absence of GBE, resulting in the accumulation of abnormally structured glycogen, known as polyglucosan bodies.[5] Glycogen buildup leads to increased osmotic pressure resulting in cellular swelling and death.[5] The tissues most affected by this disease are the liver, heart, and neuromuscular system, areas with the greatest levels of glycogen accumulation.[5][18] Abnormal glycogen buildup in the liver interferes with liver functioning and can result in an enlarged liver and liver disease.[5][19] In muscles, the inability of cells to efficiently breakdown glycogen due to the severe reduction or absence of branching can lead to muscle weakness and atrophy.[5] At least three mutations in the GBE1 gene have been found to cause another disease called adult polyglucosan body disease (APBD).[5][20] While in GSD IV GBE activity is undetectable or minimally detectable, APBD is characterized by reduced or even normal GBE activity.[20] In this disease, abnormal glycogen can build up in neurons leading to a spectrum of problems. Specifically, some disease characteristics are gait difficulties from mixed upper and lower motor neuron involvement sensory loss in lower extremities, and neurogenic bladder, a problem in which a person lacks bladder control due to a brain, spinal cord, or nerve condition.[20][21]

Model organisms

Model organisms have been used in the study of GBE1 function. A conditional knockout mouse line, called Gbe1tm1a(KOMP)Wtsi[25][26] was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.[27][28][29]

Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[23][30] Twenty six tests were carried out on mutant mice and two significant abnormalities were observed.[23] No homozygous mutant embryos were identified during gestation, and therefore none survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice; no additional significant abnormalities were observed in these animals.[23]

References

  1. ↑ 1.0 1.1 1.2 "Entrez Gene: glucan (1,4-alpha-), branching enzyme 1". Retrieved 2011-08-30.
  2. ↑ Berg J (2012). Biochemistry Seventh Edition. W.H. Freeman and Company. pp. 627–630.
  3. ↑ 3.0 3.1 National Center for Biotechnology Information. "GBE1 glucan (1,4-alpha-), branching enzyme 1 [ Homo sapiens (human) ]". US. National Library of Medicine.
  4. ↑ 4.0 4.1 Online Mendelian Inheritance in Man. "Glycogen Branching Enzyme; GBE1". Johns Hopkins University.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 Genetics Home Reference. "GBE1". U.S. National Library of Medicine.
  6. ↑ 6.0 6.1 6.2 6.3 Thon VJ, Khalil M, Cannon JF (April 1993). "Isolation of human glycogen branching enzyme cDNAs by screening complementation in yeast". The Journal of Biological Chemistry. 268 (10): 7509–13. PMID 8463281.
  7. ↑ 7.0 7.1 7.2 Abad MC, Binderup K, Rios-Steiner J, Arni RK, Preiss J, Geiger JH (November 2002). "The X-ray crystallographic structure of Escherichia coli branching enzyme". The Journal of Biological Chemistry. 44. 277 (44): 42164–70. doi:10.1074/jbc.m205746200. PMID 12196524.
  8. ↑ Pal K, Kumar S, Sharma S, Garg SK, Alam MS, Xu HE, Agrawal P, Swaminathan K (July 2010). "Crystal structure of full-length Mycobacterium tuberculosis H37Rv glycogen branching enzyme: insights of N-terminal beta-sandwich in substrate specificity and enzymatic activity". The Journal of Biological Chemistry. 285 (27): 20897–903. doi:10.1074/jbc.M110.121707. PMC 2898361. PMID 20444687.
  9. ↑ Matsuura Y, Kusunoki M, Harada W, Kakudo M (March 1984). "Structure and possible catalytic residues of Taka-amylase A". Journal of Biochemistry. 95 (3): 697–702. PMID 6609921.
  10. ↑ Buisson G, Duée E, Haser R, Payan F (December 1987). "Three dimensional structure of porcine pancreatic alpha-amylase at 2.9 A resolution. Role of calcium in structure and activity". The EMBO Journal. 6 (13): 3909–16. PMC 553868. PMID 3502087.
  11. ↑ Devillers CH, Piper ME, Ballicora MA, Preiss J (October 2003). "Characterization of the branching patterns of glycogen branching enzyme truncated on the N-terminus". Archives of Biochemistry and Biophysics. 418 (1): 34–8. doi:10.1016/S0003-9861(03)00341-2. PMID 13679080.
  12. ↑ Kuriki T, Stewart DC, Preiss J (November 1997). "Construction of chimeric enzymes out of maize endosperm branching enzymes I and II: activity and properties". The Journal of Biological Chemistry. 272 (46): 28999–9004. PMID 9360973.
  13. ↑ Palomo M, Pijning T, Booiman T, Dobruchowska JM, van der Vlist J, Kralj S, Planas A, Loos K, Kamerling JP, Dijkstra BW, van der Maarel MJ, Dijkhuizen L, Leemhuis H (February 2011). "Thermus thermophilus glycoside hydrolase family 57 branching enzyme: crystal structure, mechanism of action, and products formed". The Journal of Biological Chemistry. 286 (5): 3520–30. doi:10.1074/jbc.m110.179515. PMC 3030357. PMID 21097495.
  14. ↑ Santos CR, Tonoli CC, Trindade DM, Betzel C, Takata H, Kuriki T, Kanai T, Imanaka T, Arni RK, Murakami MT (February 2011). "Structural basis for branching-enzyme activity of glycoside hydrolase family 57: structure and stability studies of a novel branching enzyme from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1" (PDF). Proteins. 79 (2): 547–57. doi:10.1002/prot.22902. PMID 21104698.
  15. ↑ Noguchi J, Chaen K, Vu NT, Akasaka T, Shimada H, Nakashima T, Nishi A, Satoh H, Omori T, Kakuta Y, Kimura M (August 2011). "Crystal structure of the branching enzyme I (BEI) from Oryza sativa L with implications for catalysis and substrate binding". Glycobiology. 21 (8): 1108–16. doi:10.1093/glycob/cwr049. PMID 21493662.
  16. ↑ Rose S (1999). The Chemistry of LIfe. Pelican Books. pp. 199–201.
  17. ↑ McKusick VA, Kniffin CL (May 2, 2016). "OMIM Entry 263570 - Polyglucosan body neuropathy, adult form". Online Mendelian Inheritance in Man. Johns Hopkins University. Retrieved 7 March 2017.
  18. ↑ Mingyi, Chen (2011). Glycogen Storages Diseases chapter of Molecular Pathology of Liver Diseases. Springer. pp. 677–682.
  19. ↑ Bruno C, van Diggelen OP, Cassandrini D, Gimpelev M, Giuffrè B, Donati MA, Introvini P, Alegria A, Assereto S, Morandi L, Mora M, Tonoli E, Mascelli S, Traverso M, Pasquini E, Bado M, Vilarinho L, van Noort G, Mosca F, DiMauro S, Zara F, Minetti C (September 2004). "Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV)". Neurology. 63 (6): 1053–8. doi:10.1212/01.wnl.0000138429.11433.0d. PMID 15452297.
  20. ↑ 20.0 20.1 20.2 Klein, Christopher. "Adult Polyglucosan Body Disease".
  21. ↑ Hussain A, Armistead J, Gushulak L, Kruck C, Pind S, Triggs-Raine B, Natowicz MR (September 2012). "The adult polyglucosan body disease mutation GBE1 c.1076A>C occurs at high frequency in persons of Ashkenazi Jewish background". Biochemical and Biophysical Research Communications. 426 (2): 286–8. doi:10.1016/j.bbrc.2012.08.089. PMID 22943850.
  22. ↑ "Citrobacter infection data for Gbe1". Wellcome Trust Sanger Institute.
  23. ↑ 23.0 23.1 23.2 23.3 Gerdin AK (2010). "The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice". Acta Ophthalmologica. 88: 925–7. doi:10.1111/j.1755-3768.2010.4142.x.
  24. ↑ Mouse Resources Portal, Wellcome Trust Sanger Institute.
  25. ↑ "International Knockout Mouse Consortium".
  26. ↑ "Mouse Genome Informatics".
  27. ↑ Skarnes WC, Rosen B, West AP, Koutsourakis M, Bushell W, Iyer V, Mujica AO, Thomas M, Harrow J, Cox T, Jackson D, Severin J, Biggs P, Fu J, Nefedov M, de Jong PJ, Stewart AF, Bradley A (June 2011). "A conditional knockout resource for the genome-wide study of mouse gene function". Nature. 474 (7351): 337–42. doi:10.1038/nature10163. PMC 3572410. PMID 21677750.
  28. ↑ Dolgin E (June 2011). "Mouse library set to be knockout". Nature. 474 (7351): 262–3. doi:10.1038/474262a. PMID 21677718.
  29. ↑ Collins FS, Rossant J, Wurst W (January 2007). "A mouse for all reasons". Cell. 128 (1): 9–13. doi:10.1016/j.cell.2006.12.018. PMID 17218247.
  30. ↑ van der Weyden L, White JK, Adams DJ, Logan DW (June 2011). "The mouse genetics toolkit: revealing function and mechanism". Genome Biology. 12 (6): 224. doi:10.1186/gb-2011-12-6-224. PMC 3218837. PMID 21722353.

Further reading

External links

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