_EC 3.1.13.- Exoribonucleases producing 5'-phosphomonoesters. 1,716 PDB entries  
EC 3.-.-.- Hydrolases. [51,812 PDB entries]
EC 3.1.-.- Acting on ester bonds. [12,878 PDB entries]
EC 3.1.13.- Exoribonucleases producing 5'-phosphomonoesters. [1,716 PDB entries]
EC 3.1.13.1 exoribonuclease Ii. [24 PDB entries]
EC 3.1.13.2 exoribonuclease H. [1,648 PDB entries]
EC 3.1.13.3 oligonucleotidase. [-]
EC 3.1.13.4 poly(A)-specific ribonuclease. [43 PDB entries]
EC 3.1.13.5 ribonuclease D. [1 PDB entries]

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