---
title: "AdoMet MTase"
chunk: 1/1
source: "https://en.wikipedia.org/wiki/AdoMet_MTase"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T11:26:05.398611+00:00"
instance: "kb-cron"
---

S-adenosylmethionine-dependent methyltransferase (SAM-MTase or AdoMet-MTase) is a conserved protein domain and protein superfamily. SAM-MTase proteins are methyltransferases. There are five protein families within SAM-MTase, 
SAM-MTases use S-adenosyl-L-methionine as a substrate for methylation, creating the product S-adenosyl-L-homocysteine.


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

class I: Rossmann-like α/β, the largest subgroup.
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


== References ==