_EC 2.7.13.- Protein-histidine kinases. 572 PDB entries  
EC 2.-.-.- Transferases. [47,784 PDB entries]
EC 2.7.-.- Transferring phosphorus-containing groups. [28,106 PDB entries]
EC 2.7.13.- Protein-histidine kinases. [572 PDB entries]
EC 2.7.13.1 protein-histidine pros-kinase. [-]
EC 2.7.13.2 protein-histidine tele-kinase. [-]
EC 2.7.13.3 histidine kinase. [572 PDB entries]

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