This domain is found in peptide chain release factors such as RF-1 (Swiss:P07011) and RF-2 (Swiss:P07012), and a number of smaller proteins of unknown function such as Swiss:P40711. This domain contains the peptidyl-tRNA hydrolase activity. The domain contains a highly conserved motif GGQ, where the glutamine is thought to coordinate the water that mediates the hydrolysis.

1: The crystal structure of human eukaryotic release factor eRF1--mechanism of stop codon recognition and peptidyl-tRNA hydrolysis. Song H, Mugnier P, Das AK, Webb HM, Evans DR, Tuite MF, Hemmings BA, Barford D; Cell 2000;100:311-321. PMID:10676813