Methionine S-methyltransferase (IPR025779)

Short name: Met_S-MeTrfase

Overlapping homologous superfamilies


Family relationships



This entry represents the methionine S-methyltransferase (EC: family, which catalyse the S-methylmethionine (SMM) biosynthesis from adenosyl-L-homocysteine (AdoMet) and methionine [PMID: 7673218]. All flowering plants produce S-methylmethionine (SMM) from Met and have a separate mechanism to convert SMM back to Met. The functions of SMM and the reasons for its interconversion with Met are unknown [PMID: 10449582].

Methyltransferases (EC 2.1.1.-) constitute an important class of enzymes present in every life form. They transfer a methyl group most frequently from S-adenosyl L-methionine (SAM or AdoMet) to a nucleophilic acceptor such as oxygen leading to S-adenosyl-L-homocysteine (AdoHcy) and a methylated molecule [PMID: 16225687, PMID: 21858014, PMID: 12826405]. All these enzymes have in common a conserved region of about 130 amino acid residues that allow them to bind SAM [PMID: 7897657]. The substrates that are methylated by these enzymes cover virtually every kind of biomolecules ranging from small molecules, to lipids, proteins and nucleic acids [PMID: 16225687, PMID: 21858014, PMID: 7897657]. Methyltransferase are therefore involved in many essential cellular processes including biosynthesis, signal transduction, protein repair, chromatin regulation and gene silencing [PMID: 16225687, PMID: 21858014, PMID: 12826405]. More than 230 families of methyltransferases have been described so far, of which more than 220 use SAM as the methyl donor.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0008168 methyltransferase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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