Homologous Superfamily

Peptide Chain Release Factor eRF1/aRF1, N-terminal (IPR024049)

Short name: Release_factor_eRF1/aRF1_N

Overlapping entries


Terminating protein synthesis on the ribosome requires the presence of a class I polypeptide chain release factor (RF) to induce peptidyl-tRNA hydrolysis. Bacteria possess two class I RFs; RF1 which recognises UAG and UAA, and RF2 which recognises UGA and UAA. Mitochondrial RFs are related structurally and functionally to those of bacteria. Eukaryotes posses only a single class 1 factor, eRF1, which recognises all three termination codons. Similarly, in all archaeal species where the complete sequence of the genome is available, only a single class I factor, aRF1, has been identified so far. The aRF1 family is highly homologous to the eRF1 family, indicating a common origin and ancestor molecule. The bacterial and mitochondrial class I RFs show no significant sequence similarity with their eukaryotic and archaeal counterparts and are considered to form a separate family. For more information see [PMID: 9179839, PMID: 10471834, PMID: 10788613].

The release factor eRF1 terminates protein biosynthesis by recognising stop codons at the A site of the ribosome and stimulating peptidyl-tRNA bond hydrolysis at the peptidyl transferase centre. The crystal structure of human eRF1 is known [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 position of the essential GGQ motif at an exposed tip of domain 2 suggests that the Gln residue coordinates a water molecule to mediate the hydrolytic activity at the peptidyl transferase centre. A conserved groove on domain 1 is proposed to form the codon recognition site [PMID: 10676813].

This entry represents the N-terminal domain (domain 1) of the release factors from eukaryota and archaea (eRF1 and aRF1).

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.