Structural domains which comprise this superfamily share the structure of a conserved region in the release factor eRF1, designated domain 1. eRF1 is involved in termination of protein biosynthesis through stop codon recognition at the A site of the ribosome and stimulation of peptidyl-tRNA bond hydrolysis at the peptidyl transferase centre PMID:10676813. The overall shape and dimensions of eRF1 resemble a tRNA molecule with domains 1, 2, and 3 of eRF1 corresponding to the anticodon loop, aminoacyl acceptor stem, and T stem of a tRNA molecule, respectively. The presence of the essential GGQ motif at an exposed tip of domain 2 suggests that this motif plays a direct role at the catalytic site of the peptidyl transferase center PMID:10676813.