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S-adenosylmethionine synthetase

Methionine adenosyltransferase
5a1i.jpg
S-adenosylmethionine synthase 2, tetramer, Human
Identifiers
EC number 2.5.1.6
CAS number 9012-52-6
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
S-adenosylmethionine synthetase N terminal domain
PDB 1mxb EBI.jpg
S-adenosylmethionine synthetase with ADP
Identifiers
Symbol S-AdoMet_synt_N
Pfam PF00438
InterPro IPR022628
PROSITE PDOC00369
SCOP 1mxa
SUPERFAMILY 1mxa
S-adenosylmethionine synthetase Central domain
PDB 1mxb EBI.jpg
S-adenosylmethionine synthetase with ADP
Identifiers
Symbol S-AdoMet_synt_M
Pfam PF02772
InterPro IPR022629
PROSITE PDOC00369
SCOP 1mxa
SUPERFAMILY 1mxa
S-adenosylmethionine synthetase, C-terminal domain
PDB 1o92 EBI.jpg
Methionine adenosyltransferase in a complex ADP and l-methionine.
Identifiers
Symbol S-AdoMet_synt_C
Pfam PF02773
InterPro IPR022630
PROSITE PDOC00369
SCOP 1mxa
SUPERFAMILY 1mxa

S-adenosylmethionine synthetase (EC 2.5.1.6) (also known as methionine adenosyltransferase (MAT)) is an enzyme that creates S-adenosylmethionine (a.k.a. AdoMet, SAM or SAMe) by reacting methionine (a non-polar amino acid) and ATP (the basic currency of energy).

AdoMet is a methyl donor for transmethylation. It gives away its methyl group and is also the propylamino donor in polyamine biosynthesis. S-adenosylmethionine synthesis can be considered the rate-limiting step of the methionine cycle.

As a methyl donor SAM allows DNA methylation. Once DNA is methylated, it switches the genes off and therefore, S-adenosylmethionine can be considered to control gene expression.

SAM is also involved in gene transcription, cell proliferation, and production of secondary metabolites. Hence SAM synthetase is fast becoming a drug target, in particular for the following diseases: depression, dementia, vacuolar myelopathy, liver injury, migraine, osteoarthritis, and as a potential cancer chemopreventive agent.

This article discusses the protein domains that make up the SAM synthetase enzyme and how these domains contribute to its function. More specifically, this article explores the shared pseudo-3-fold symmetry that makes the domains well-adapted to their functions.


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Wikipedia

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