| Except where noted otherwise, data are given for|
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references
Cyclic ADP Ribose, popularly known as cADPR, is a cyclic adenine nucleotide (like cAMP) with two phosphate groups present on 5' OH of the adenosine (like ADP), further connected to another ribose at the 5' position, which, in turn, closes the cycle by glycosidic bonding to the Nitrogen1 of the same Adenine base (whose position 9 has the glycosidic bond to the other ribose). It is produced from nicotinamide adenine dinucleotide (NAD+) by ADP-ribosyl cyclases (EC 184.108.40.206) as part of a second messenger system.
cADPR is a cellular messanger for calcium signaling. It is the physiological allosteric modulator of the ryanodine receptor (RyR), which stimulates calcium-induced calcium release (CICR) at lower cytosolic concentrations. RyR activation with high concentration of caffeine is partly due to caffeine's mimicking the binding of cADPRs to RyRs. Whether the action is by direct binding to RyR or indirect (through binding with FKBP12.6) is debated. Some reports suggest that cADPR binding makes FKBP12.6, which normally binds RyR2, to fall off the RYR2.
cADPR is synthesized from NAD+ by the bifunctional ectoenzymes of the CD38 family (also includes ADP ribosyl cyclase of Aplysia and GPI anchored CD157). The same enzymes are also capable of hydrolyzing it to ADPR. Catalysis proceeds via a covalently-bound intermediate. The hydrolysis reaction is inhibited by ATP, and the cyclic form of APDR may accumulate.
- ↑ Guse AH (2004). "Regulation of calcium signaling by the second messenger cyclic adenosine diphosphoribose (cADPR)". Curr. Mol. Med. 4 (3): 239-48. PMID 15101682.
- ↑ Guse AH (2004). "Biochemistry, biology, and pharmacology of cyclic adenosine diphosphoribose (cADPR)". Curr. Med. Chem. 11 (7): 847-55. PMID 15078169.
Lee, H.C., Walseth, T.F., Bratt, G.T., Hayes, R.N., and Clapper, D.L. (1989) Structural determination of a cyclic metabolite of NAD+ with intracellular Ca+2 mobilizing activity. J. Biol. Chem. 264, 1608-1615.
Lee, H.C., Aarhus, R. and Levitt, D. (1994) The crystal structure of cyclic ADP-ribose. Nature Structural Biology 1, 143-144.
Prasad, G.S., McRee, D.E., Stura, E.A., Levitt, D.G., Lee, H.C., Stout, C.D. (1996) Crystal structure of Aplysia ADP-ribosyl cyclase, a homolog of the bifunctional ectozyme CD38. Nature Struct. Biol. 3, 957-964.
Liu, Q., Kriksunov, I.A., Graeff, R., Munshi, C. Lee, H.C. and Hao, Q. (2005) Crystal structure of the human CD38 extracellular domain. Structure 13, 1331-1339.
Cell signaling: calcium signaling
|Second messengers||IP3 - NAADP - cADPR|
|Intracellular calcium store gates||IP3 receptor - Ryanodine receptor - putative NAADP receptor|
|Calcium pumps and exchangers||SERCA - Na/Ca antiport - Ca/H antiport|
|calcium binding protein domains||EF hand domain - C2 domain|
|Calcium based molecular switches, and kinases||Troponin C - CaM - CaM kinases - PKC - NCS|
|Intracellular calcium chelators (calcium buffers) and calcium sensors||Calbindin - S100 - pervalbumin - Calretinin - Calsequestrin - Sarcalumenin - Phospholamban - Synaptotagmins|
|Calcium dependent proteases||Calpain|
|Calcium dependent cytoskeleton remodeling proteins||Gelsolin|
|Cell membrane calcium channels||VDCC - TRP - NMDA receptor - AMPA receptor - 5-HT3 receptor - P2X Receptor|
|Calcium regulated chaperones||calreticulin - calnexin|
|Calcium based adhesion molecules||Cadherin|
|Calcium homeostasis||Parathyroid hormone - Calcitonin - calcium receptor - vitamin D|
|Nucleobases:||Purine (Adenine, Guanine) | Pyrimidine (Uracil, Thymine, Cytosine)|
|Nucleosides:||Adenosine/Deoxyadenosine | Guanosine/Deoxyguanosine | Uridine | Thymidine | Cytidine/Deoxycytidine|
|Nucleotides:||monophosphates (AMP, GMP, UMP, CMP) | diphosphates (ADP, GDP, UDP, CDP) | triphosphates (ATP, GTP, UTP, CTP) | cyclic (cAMP, cGMP, cADPR)|
|Deoxynucleotides:||monophosphates (dAMP, dGMP, TMP, dCMP) | diphosphates (dADP, dGDP, TDP, dCDP) | triphosphates (dATP, dGTP, TTP, dCTP)|
|Ribonucleic acids:||RNA | mRNA | tRNA | rRNA | gRNA | miRNA | ncRNA | piRNA | shRNA | siRNA | snRNA | snoRNA|
|Deoxyribonucleic acids:||DNA | mtDNA | cDNA|
|Nucleic acid analogues:||GNA | LNA | PNA | TNA | morpholino|
|Cloning vectors:||plasmid | cosmid | fosmid | phagemid | BAC | YAC | HAC|
There is no pharmaceutical or device industry support for this site and we need your viewer supported Donations | Editorial Board | Governance | Licensing | Disclaimers | Avoid Plagiarism | Policies