S-adenosylmethionine synthetase (IPR002133)

Short name: S-AdoMet_synthetase

Overlapping homologous superfamilies

Family relationships



S-adenosylmethionine synthetase (MAT, EC: is the enzyme that catalyzes the formation of S-adenosylmethionine (AdoMet) from methionine and ATP [PMID: 1696256]. AdoMet is an important methyl donor for transmethylation and is also the propylamino donor in polyamine biosynthesis.

In bacteria there is a single isoform of AdoMet synthetase (gene metK), there are two in budding yeast (genes SAM1 and SAM2) and in mammals while in plants there is generally a multigene family.

The sequence of AdoMet synthetase is highly conserved throughout isozymes and species. The active sites of both the Escherichia coli and rat liver MAT reside between two subunits, with contributions from side chains of residues from both subunits, resulting in a dimer as the minimal catalytic entity. The side chains that contribute to the ligand binding sites are conserved between the two proteins. In the structures of complexes with the E. coli enzyme, the phosphate groups have the same positions in the (PPi plus Pi) complex and the (ADP plus Pi) complex and are located at the bottom of a deep cavity with the adenosyl group nearer the entrance [PMID: 1213535].

GO terms

Biological Process

GO:0006556 S-adenosylmethionine biosynthetic process

Molecular Function

GO:0005524 ATP binding
GO:0004478 methionine adenosyltransferase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.