A subclass of transferases that transfer chemical groups containing a single carbon. These include the METHYLTRANSFERASES, the HYDROXYMETHYL AND FORMYL TRANSFERASES, the CARBOXYL AND CARBAMOYL TRANSFERASES, and the AMIDINOTRANSFERASES. EC 2.1.

Synonyms: EC 2.1.-, One-Carbon Group Transferases, One Carbon Group Transferases, Transferases, Single-Carbon Group, Transferases, One-Carbon Group, Single Carbon Group Transferases, Single-Carbon Group Transferases