_EC 2.1.-.- Transferring one-carbon groups. 5,181 PDB entries  
EC 2.-.-.- Transferases. [47,784 PDB entries]
EC 2.1.-.- Transferring one-carbon groups. [5,181 PDB entries]
EC 2.1.1.- Methyltransferases. [4,592 PDB entries]
EC 2.1.2.- Hydroxymethyl-, formyl- and related transferases. [304 PDB entries]
EC 2.1.3.- Carboxy- and carbamoyltransferases. [273 PDB entries]
EC 2.1.4.- Amidinotransferases. [12 PDB entries]
EC 2.1.5.- Methylenetransferases. [-]

[-] signifies that there are no PDB entries for the given enzyme subclass