Eukaryotic release factors

Eukaryotic translation termination factor 1 (eRF1), also known asTB3-1, is a is_associated_with::protein that in humans is encoded by the ETF1 is_associated_with::gene.

In is_associated_with::eukaryotes, this is the only release factor (eRF) which recognizes all three is_associated_with::stop codons. The overall process of termination is similar in prokaryotes, but in the latter 3 separate release factors exist, RF1, RF and RF3.

Function
Termination of protein biosynthesis and release of the nascent polypeptide chain are signaled by the presence of an in-frame stop codon at the aminoacyl site of the ribosome. The process of translation termination is universal and is mediated by protein release factors (RFs) and GTP. A class 1 RF recognizes the stop codon and promotes the hydrolysis of the ester bond linking the polypeptide chain with the peptidyl site tRNA, a reaction catalyzed at the peptidyl transferase center of the ribosome. Class 2 RFs, which are not codon specific and do not recognize codons, stimulate class 1 RF activity and confer GTP dependency upon the process. In prokaryotes, both class 1 RFs, RF1 and RF2, recognize UAA; however, UAG and UGA are decoded specifically by RF1 and RF2, respectively. In eukaryotes, eRF1, or ETF1, the functional counterpart of RF1 and RF2, functions as an omnipotent RF, decoding all 3 stop codons.