A highly conserved eukaryotic protein family possessing properties of polypeptide chain release factor

THE termination of protein synthesis in ribosomes is governed by termination (stop) codons in messenger RNAs and by polypeptide chain release factors (RFs). Although the primary structure of prokaryotic RFs and yeast mitochrondrial RF is established1–4, that of the only known eukaryotic RF (eRF)5 remains obscure. Here we report the assignment of a family of tightly related proteins (designated eRFl) from lower and higher eukaryotes which are structurally and functionally similar to rabbit eRF. Two of these proteins, one from human6 and the other from Xenopus laevis7 , have been expressed in yeast and Escherichia coli, respectively, purified and shown to be active in the in vitro RF assay. The other protein of this family, sup45 (supl) of Saccharomyces cerevisiae, is involved in omnipotent suppression during translation8–12. The amino-acid sequence of the eRFl family is highly conserved. We conclude that the eRFl proteins are directly implicated in the termination of translation in eukaryotes.

[1]  G. Spedding.  Ribosomes and protein synthesis : a practical approach , 1990 .

[2]  W. Tate,et al.  Characterization of reticulocyte release factor. , 1977, The Journal of biological chemistry.

[3]  A. Beaudet,et al.  Peptide chain termination with mammalian release factor. , 1970, Proceedings of the National Academy of Sciences of the United States of America.

[4]  A. Beaudet,et al.  Mammalian release factor; in vitro assay and purification. , 1974, Methods in Enzymology.

[5]  L. Grivell,et al.  Sequence comparison of new prokaryotic and mitochondrial members of the polypeptide chain release factor family predicts a five-domain model for release factor structure. , 1992, Nucleic acids research.

[6]  J. Beggs.  Transformation of yeast by a replicating hybrid plasmid , 1978, Nature.

[7]  J. Friesen,et al.  Isolation of the SUP45 omnipotent suppressor gene of Saccharomyces cerevisiae and characterization of its gene product , 1985, Molecular and cellular biology.

[8]  L. Mora,et al.  Localization and characterization of the gene encoding release factor RF3 in Escherichia coli. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[9]  J. Vandekerckhove,et al.  Microsequencing of proteins recorded in human two‐dimensional gel protein databases , 1991, Electrophoresis.

[10]  I. Stansfield,et al.  Ribosomal association of the yeast SAL4 (SUP45) gene product: implications for its role in translation fidelity and termination , 1992, Molecular microbiology.

[11]  Timothy J. Mitchison,et al.  Mitotic spindle organization by a plus-end-directed microtubule motor , 1992, Nature.

[12]  M. Jacquet,et al.  In Xenopus laevis, the product of a developmentally regulated mRNA is structurally and functionally homologous to a Saccharomyces cerevisiae protein involved in translation fidelity , 1993, Molecular and cellular biology.

[13]  A. Beaudet,et al.  Mammalian peptide chain termination. II. Codon specificity and GTPase activity of release factor. , 1971, Proceedings of the National Academy of Sciences of the United States of America.

[14]  P. Breining,et al.  Yeast omnipotent supressor SUP1 (SUP45): nucleotide sequence of the wildtype and a mutant gene , 1986, Nucleic Acids Res..

[15]  M. Sudomoina,et al.  Cloning and nucleotide sequence of the structural gene encoding for human tryptophanyl-tRNA synthetase. , 1991, Gene.

[16]  L. Grivell,et al.  The yeast nuclear gene MRF1 encodes a mitochondrial peptide chain release factor and cures several mitochondrial RNA splicing defects. , 1992, Nucleic acids research.

[17]  V. Trézéguet,et al.  A mammalian tryptophanyl-tRNA synthetase shows little homology to prokaryotic synthetases but near identity with mammalian peptide chain release factor. , 1991, Biochemistry.

[18]  W. Craigen,et al.  Recent advances in peptide chain termination , 1990, Molecular microbiology.

[19]  W. Tate,et al.  Mammalian polypeptide chain release factor and tryptophanyl‐tRNA synthetase are distinct proteins. , 1993, The EMBO journal.

[20]  H. Grenett,et al.  Identification of a human cDNA with high homology to yeast omnipotent suppressor 45. , 1992, Gene.

[21]  Y. Nakamura,et al.  Identification of the prfC gene, which encodes peptide-chain-release factor 3 of Escherichia coli. , 1994, Proceedings of the National Academy of Sciences of the United States of America.