Protein glutaminase (PG, EC 3.5.1.44) can deamidate glutamine residues in proteins to glutamate residues. This entry represents the mature PG enzyme which bears partial homology to factor XIII-like Transglutaminase (TG), especially its Cys-His-Asp catalytic triad. A similar triad (Cys-His-Asn) is also shared by some cysteine proteases such as papain and actinidin. The mature PG is a monomer enzyme consisting of 185 amino acid residues [1].

1: Crystal structures of protein glutaminase and its pro forms converted into enzyme-substrate complex. Hashizume R, Maki Y, Mizutani K, Takahashi N, Matsubara H, Sugita A, Sato K, Yamaguchi S, Mikami B; J Biol Chem. 2011;286:38691-38702. PMID:21926168