The translation machinery and 70 kd heat shock protein cooperate in protein synthesis.
The function of the yeast SSB 70 kd heatshock proteins (hsp70s) was investigated by a variety of approaches. The SSB hsp70s (Ssb1/2p) are associated with translating ribosomes. This association is disrupted by puromycin, suggesting that Ssb1/2p may bind directly to the nascent polypeptide. Mutant ssb1 ssb2 strains grow slowly, contain a low number of translating ribosomes, and are hypersensitive to several inhibitors of protein synthesis. The slow growth phenotype of ssb1 ssb2 mutants is suppressed by increased copy number of a gene encoding a novel translation elongation factor 1 alpha (EF-1 alpha)-like protein. We suggest that cytosolic hsp70 aids in the passage of the nascent polypeptide chain through the ribosome in a manner analogous to the role played by organelle-localized hsp70 in the transport of proteins across membranes.
Nelson
R J
RJ
Department of Biomolecular Chemistry, University of Wisconsin-Madison 53706.
Ziegelhoffer
T
T
Nicolet
C
C
Werner-Washburne
M
M
Craig
E A
EA
D000595:Amino Acid Sequence; D001483:Base Sequence; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology*; D011691:Puromycin / Q000494:pharmacology; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; C077247:HBS1 protein, S cerevisiae; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D011691:Puromycin; D019204:GTP-Binding Proteins