title: Conserved motifs in prokaryotic and eukaryotic polypeptide release factors: tRNA-protein mimicry hypothesis.
abstract: Translation termination requires two codon-specific polypeptide release factors in prokaryotes and one omnipotent factor in eukaryotes. Sequences of 17 different polypeptide release factors from prokaryotes and eukaryotes were compared. The prokaryotic release factors share residues split into seven motifs. Conservation of many discrete, perhaps critical, amino acids is observed in eukaryotic release factors, as well as in the C-terminal portion of elongation factor (EF) G. Given that the C-terminal domains of EF-G interacts with ribosomes by mimicry of a tRNA structure, the pattern of conservation of residues in release factors may reflect requirements for a tRNA-mimicry for binding to the A site of the ribosome. This mimicry would explain why release factors recognize stop codons and suggests that all prokaryotic and eukaryotic release factors evolved from the progenitor of EF-G.
authors.affiliation: Department of Tumor Biology, Institute of Medical Science, University of Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Ebihara
authors.forename: M
authors.initials: M
authors.lastname: Uno
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D008961:Models, Structural; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010443:Peptide Chain Termination, Translational; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors / Q000737:chemistry* / Q000378:metabolism; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D012343:RNA, Transfer / Q000737:chemistry*; D012360:RNA, Transfer, Phe / Q000737:chemistry; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis
chemical_list: D005656:Fungal Proteins; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D010454:Peptide Termination Factors; D012360:RNA, Transfer, Phe; C080775:SUP45 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012343:RNA, Transfer