Peptide-chain elongation in eukaryotes.
The elongation phase of translation leads to the decoding of the mRNA and the synthesis of the corresponding polypeptide chain. In most eukaryotes, two distinct protein elongation factors (eEF-1 and eEF-2) are required for elongation. Each is active as a complex with GTP. eEF-1 is a multimer and mediates the binding of the cognate aminoacyl-tRNA to the ribosome, while eEF-2, a monomer, catalyses the movement of the ribosome relative to the mRNA. Recent work showing that bacterial ribosomes possess three sites for tRNA binding and that during elongation tRNAs may occupy 'hybrid' sites is incorporated into a model of eukaryotic elongation. In fungi, elongation also requires a third factor, eEF-3. A number of mechanisms exist to promote the accuracy or 'fidelity' of elongation: eEF-3 may play a role here. cDNAs for this and the other elongation factors have been cloned and sequenced, and the structural and functional properties of the elongation factors are discussed. eEF-1 and eEF-2 can be regulated by phosphorylation, and this may serve to control rates of elongation in vivo.
Department of Biochemistry, School of Medical Sciences, University of Bristol, UK.
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D000818:Animals; D005057:Eukaryotic Cells / Q000378:metabolism; D005656:Fungal Proteins; D006801:Humans; D008954:Models, Biological; D010441:Peptide Chain Elongation, Translational; D020648:Peptide Elongation Factor 1; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000378:metabolism; D014176:Protein Biosynthesis; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D020648:Peptide Elongation Factor 1; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D012346:RNA, Transfer, Amino Acyl; D029701:Saccharomyces cerevisiae Proteins; C111584:YEF3 protein, S cerevisiae