_EC 2.1.-.- Transferring one-carbon groups. 1,783 PDB entries  
EC 2.-.-.- Transferases. [19,022 PDB entries]
EC 2.1.-.- Transferring one-carbon groups. [1,783 PDB entries]    
EC 2.1.1.- Methyltransferases. [1,448 PDB entries]
EC 2.1.2.- Hydroxymethyl-, formyl- and related transferases. [165 PDB entries]
EC 2.1.3.- Carboxyl- and carbamoyltransferases. [158 PDB entries]
EC 2.1.4.- Amidinotransferases. [12 PDB entries]