5-Methyltetrahydrofolate-homocysteine methyltransferase

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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]

Contents 1 Function 2 See also 3 References 4 External links

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

See also

• methyltransferase
• Arakawa's syndrome II
• 5-methyltetrahydrofolate

References

External links

• ENZYME: EC 2.1.1.13
• MeSH 5-Methyltetrahydrofolate-Homocysteine+S-Methyltransferase

v • d • 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

v • d • e Amino acid metabolism enzymes (essential in CAPS)
K	LYSINE→acetyl-CoA Saccharopine dehydrogenase - Glutaryl-CoA dehydrogenase LEUCINE→acetyl-CoA Branched-chain alpha-keto acid dehydrogenase complex - Isovaleryl coenzyme A dehydrogenase - Methylcrotonyl-CoA carboxylase TRYPTOPHAN→acetyl-CoA Kynureninase PHENYLALANINE→tyrosine→acetoacetate (see below)
G	glycine→serine→pyruvate→TCA Serine hydroxymethyltransferase - Serine dehydratase alanine→pyruvate→TCA Alanine transaminase cysteine→pyruvate→TCA D-cysteine desulfhydrase threonine→pyruvate→TCA L-threonine dehydrogenase HISTIDINE→glutamate Histidine ammonia-lyase - Urocanate hydratase - Formiminotransferase cyclodeaminase proline→glutamate Proline oxidase - Pyrroline-5-carboxylate reductase - 1-Pyrroline-5-carboxylate dehydrogenase/ALDH4A1 - PYCR1 arginine→glutamate Ornithine aminotransferase - Ornithine decarboxylase - Agmatinase glutamate→alpha-ketoglutarate→TCA Glutamate dehydrogenase METHIONINE→propionyl-CoA Methionine adenosyltransferase - Adenosylhomocysteinase - (or MTR/Homocysteine methyltransferase) - Cystathionine beta synthase - Cystathionine gamma-lyase ISOLEUCINE/valine→propionyl-CoA Branched-chain alpha-keto acid dehydrogenase complex
NT	HISTIDINE→histamine Histidine decarboxylase tyrosine→dopamine→epinephrine Tyrosine hydroxylase - Aromatic L-amino acid decarboxylase - Dopamine beta hydroxylase - Phenylethanolamine N-methyltransferase - Catechol-O-methyl transferase glutamate→GABA Glutamate decarboxylase arginine→NO Nitric oxide synthase
Other	tyrosine→melanin Tyrosinase TRYPTOPHAN→serotonin→melatonin Tryptophan hydroxylase - Aromatic L-amino acid decarboxylase - Acetylserotonin O-methyltransferase cysteine+glutamate→glutathione Gamma-glutamylcysteine synthetase - Glutathione synthetase glycine→creatine Guanidinoacetate N-methyltransferase - Creatine kinase glutamate→glutamine Glutamine synthetase - Glutaminase collagen Prolyl hydroxylase - Lysyl hydroxylase
see also disorders, intermediates

he:מתיונין סינתאז