5-Methyltetrahydrofolate-homocysteine methyltransferase

5-methyltetrahydrofolate-homocysteine methyltransferase
Identifiers
Symbol	MTR
Entrez	4548
HUGO	7468
OMIM	156570
RefSeq	NM_000254
UniProt	Q99707
Other data
EC number	2.1.1.13
Locus	Chr. 1 q43

5-Methyltetrahydrofolate-homocysteine methyltransferase or (MTR) is an enzyme responsible for the production of methionine from homocysteine. MTR forms part of the S-adenosyl methionine cycle and is also called methionine synthase.^[1]

Function

MTR contains the cofactor - methylcobalamin (MeB₁₂) and uses the substrates N5-methyl-tetrahydrofolate (N⁵-methyl-THF) and homocysteine.

The enzyme works in two steps in a ping-pong reaction. First, methylcobalamin is formed by a methyl group transfer from N⁵-mTHF with formation of MeB₁₂ and tetrahydrofolate (THF). In the second step, MeB₁₂ transfers this methyl group to (homocysteine), regenerating the cofactor cobalamin and releasing the product methionine

File:VitaminB12 2.png

The MTR reaction

References

↑ Banerjee RV, Matthews RG (1990). "Cobalamin-dependent methionine synthase" (PDF). FASEB J. 4 (5): 1450–9. PMID 2407589.

External links

ENZYME: EC 2.1.1.13
5-Methyltetrahydrofolate-Homocysteine+S-Methyltransferase at the US National Library of Medicine Medical Subject Headings (MeSH)

This transferase article is a stub. You can help Wikipedia by expanding it.

v t e Transferase: one carbon transferases (EC 2.1)
2.1.1 - Methyltransferases	5-hydroxyindole-O-methyltransferase/Acetylserotonin O-methyltransferase - Betaine-homocysteine methyltransferase - Catechol-O-methyl transferase - Histamine N-methyltransferase - Homocysteine methyltransferase - 5-Methyltetrahydrofolate-homocysteine methyltransferase - Phosphatidyl ethanolamine methyltransferase - Phenylethanolamine N-methyltransferase - DNMT3B - Histone methyltransferase - Thymidylate synthase - Tryptamine N-methyltransferase - DNA methyltransferase
2.1.2 - Hydroxy methyl-, Formyl- and Related Transferases	Serine hydroxymethyltransferase - Phosphoribosylglycinamide formyltransferase - Inosine monophosphate synthase - Glutamate formimidoyltransferase - Aminomethyltransferase
2.1.3 - Carboxy- and Carbamoyl transferases	Ornithine transcarbamylase
2.1.4 - Amidino transferases	Arginine:glycine amidinotransferase

Metabolism: Protein metabolism, synthesis and catabolism enzymes

Essential amino acids are in Capitals

K→acetyl-CoA

LYSINE→	Saccharopine dehydrogenase Glutaryl-CoA dehydrogenase
LEUCINE→	3-Hydroxybutyryl-CoA dehydrogenase Branched-chain amino acid aminotransferase Branched-chain alpha-keto acid dehydrogenase complex Enoyl-CoA hydratase HMG-CoA lyase HMG-CoA reductase Isovaleryl coenzyme A dehydrogenase α-Ketoisocaproate dioxygenase Leucine 2,3-aminomutase Methylcrotonyl-CoA carboxylase Methylglutaconyl-CoA hydratase (See Template:Leucine metabolism in humans – this diagram does not include the pathway for β-leucine synthesis via leucine 2,3-aminomutase)
TRYPTOPHAN→	Indoleamine 2,3-dioxygenase/Tryptophan 2,3-dioxygenase Arylformamidase Kynureninase 3-hydroxyanthranilate oxidase Aminocarboxymuconate-semialdehyde decarboxylase Aminomuconate-semialdehyde dehydrogenase
PHENYLALANINE→tyrosine→	(see below)

G→pyruvate
→citrate

glycine→serine→	Serine hydroxymethyltransferase Serine dehydratase glycine→creatine: Guanidinoacetate N-methyltransferase Creatine kinase
alanine→	Alanine transaminase
cysteine→	D-cysteine desulfhydrase
threonine→	L-threonine dehydrogenase

G→glutamate→
α-ketoglutarate

HISTIDINE→	Histidine ammonia-lyase Urocanate hydratase Formiminotransferase cyclodeaminase
proline→	Proline oxidase Pyrroline-5-carboxylate reductase 1-Pyrroline-5-carboxylate dehydrogenase/ALDH4A1 PYCR1
arginine→	Ornithine aminotransferase Ornithine decarboxylase Agmatinase
→alpha-ketoglutarate→TCA	Glutamate dehydrogenase
Other	cysteine+glutamate→glutathione: Gamma-glutamylcysteine synthetase Glutathione synthetase Gamma-glutamyl transpeptidase glutamate→glutamine: Glutamine synthetase Glutaminase

G→propionyl-CoA→
succinyl-CoA

VALINE→	Branched-chain amino acid aminotransferase Branched-chain alpha-keto acid dehydrogenase complex Enoyl-CoA hydratase 3-hydroxyisobutyryl-CoA hydrolase 3-hydroxyisobutyrate dehydrogenase Methylmalonate semialdehyde dehydrogenase
ISOLEUCINE→	Branched-chain amino acid aminotransferase Branched-chain alpha-keto acid dehydrogenase complex 3-hydroxy-2-methylbutyryl-CoA dehydrogenase
METHIONINE→	generation of homocysteine: Methionine adenosyltransferase Adenosylhomocysteinase regeneration of methionine: Methionine synthase/Homocysteine methyltransferase Betaine-homocysteine methyltransferase conversion to cysteine: Cystathionine beta synthase Cystathionine gamma-lyase
THREONINE→	Threonine aldolase
→succinyl-CoA→TCA	Propionyl-CoA carboxylase Methylmalonyl CoA epimerase Methylmalonyl-CoA mutase

G→fumarate

PHENYLALANINE→tyrosine→	Phenylalanine hydroxylase Tyrosine aminotransferase 4-Hydroxyphenylpyruvate dioxygenase Homogentisate 1,2-dioxygenase Fumarylacetoacetate hydrolase tyrosine→melanin: Tyrosinase

G→oxaloacetate

asparagine→aspartate→	Asparaginase/Asparagine synthetase Aspartate transaminase

he:מתיונין סינתאז

5-Methyltetrahydrofolate-homocysteine methyltransferase

Contents

Function

See also

References

External links

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