AdoMet MTase

S-adenosylmethionine-dependent methyltransferase (SAM-MTase or AdoMet-MTase) is a conserved protein domain and protein superfamily.^[1] SAM-MTase proteins are methyltransferases.^[2] There are five protein families within SAM-MTase,

SAM-dependent MTases superfamily
Cartoon representation of the molecular structure of the Crystal Structure of the SAM Dependent Methyltransferase from Agrobacterium tumefaciens (PDB: 2igt​)
Identifiers
Symbol	SAM-dependent_MTases
ECOD	2003.1.5
InterPro	IPR029063

AdoMet_MTase
Identifiers
Symbol	AdoMet_MTase
Pfam	PF07757
Pfam clan	CL0063
InterPro	IPR011671
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

SAM-MTases use S-adenosyl-L-methionine as a substrate for methylation, creating the product S-adenosyl-L-homocysteine.^[3]

Structure and subgroups

All SAM-MTases contain a structurally conserved SAM-binding domain consisting of a central seven-stranded beta-sheet that is flanked by three alpha-helices per side of the sheet.^[4]

A review published in 2003 divides all methyltransferases into 5 main classes based on the structure of their catalytic domain (fold):^[5]

• class I: Rossmann-like α/β, the largest subgroup.^[3]
• class II: TIM β/α-barrel α/β
• class III: tetrapyrrole methylase α/β
• class IV: SPOUT α/β
• class V: SET domain all β