{PDOC00607} {PS00745; RF_PROK_I} {BEGIN} ******************************************************************** * Prokaryotic-type class I peptide chain release factors signature * ******************************************************************** Peptide chain release factors (RFs) are required for the termination of protein biosynthesis [1]. At present two classes of RFs can be distinguished. Class I RFs bind to ribosomes that have encountered a stop codon at their decoding site and induce release of the nascent polypeptide. Class II RFs are GTP-binding proteins that interact with class I RFs and enhance class I RF activity. In prokaryotes there are two class I RFs that act in a codon specific manner [2]: RF-1 (gene prfA) mediates UAA and UAG-dependent termination while RF-2 (gene prfB) mediates UAA and UGA-dependent termination. RF-1 and RF-2 are structurally and evolutionary related proteins which have been shown [3] to make up a family that also contains the following proteins: - Fungal MRF1, a mitochondrial RF (m-RF) which recognizes the UAA and UAG codons. - Escherichia coli RF-H, a protein of unknown function. - Escherichia coli hypothetical protein yaeJ and a close Pseudomonas putida homolog. We use as a signature pattern a highly conserved region located in the central part of the 40 to 45 Kd RF-1/2 and m-RF and in the N-terminal of the 15 to 16 Kd RF-H and yaeJ. -Consensus pattern: [ARH]-[STA]-x-G-x-G-G-Q-[HNGCSY]-[VI]-N-x(3)-[ST]-[AKG]- [IV] -Sequences known to belong to this class detected by the pattern: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Note: Prokaryotic-type class I RFs display no significant sequence similarity to prokaryotic-type class II which belong to the family of GTP-binding elongation factors (see ) nor to eukaryotic class I or class II RFs. -Expert(s) to contact by email: Tate W.P.; wptate@sanger.otago.ac.nz -Last update: December 2004 / Pattern and text revised. [ 1] Tate W.P., Poole E.S., Mannering S.M. Prog. Nucleic Acids. Res. Mol. Biol. 52:293-335(1996). [ 2] Craigen W.J., Lee C.C., Caskey C.T. "Recent advances in peptide chain termination." Mol. Microbiol. 4:861-865(1990). PubMed=2215213 [ 3] Pel H.J., Rep M., Grivell L.A. "Sequence comparison of new prokaryotic and mitochondrial members of the polypeptide chain release factor family predicts a five-domain model for release factor structure." Nucleic Acids Res. 20:4423-4428(1992). PubMed=1408743 -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}