Abstract
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.
MeSH terms
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Amino Acid Sequence
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Base Sequence
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Fungal Proteins / biosynthesis
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Fungal Proteins / chemistry
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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GTP-Binding Proteins*
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HSP70 Heat-Shock Proteins*
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Heat-Shock Proteins / chemistry
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Heat-Shock Proteins / metabolism*
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Molecular Sequence Data
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Peptide Elongation Factor 1
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Peptide Elongation Factors / chemistry
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Peptide Elongation Factors / genetics
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Peptide Elongation Factors / metabolism*
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Protein Biosynthesis / drug effects
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Protein Biosynthesis / physiology*
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Puromycin / pharmacology
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Ribonucleoproteins / chemistry
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Ribonucleoproteins / genetics
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Ribonucleoproteins / metabolism*
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Ribosomes / metabolism*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins*
Substances
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Fungal Proteins
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HBS1 protein, S cerevisiae
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HSP70 Heat-Shock Proteins
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Heat-Shock Proteins
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Peptide Elongation Factor 1
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Peptide Elongation Factors
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Ribonucleoproteins
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Saccharomyces cerevisiae Proteins
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Puromycin
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GTP-Binding Proteins
Associated data
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GENBANK/L04285
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GENBANK/M98437
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GENBANK/S47136
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GENBANK/S47137
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GENBANK/S47164
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GENBANK/S47165
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GENBANK/S47166
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GENBANK/S47167
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GENBANK/S47168
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GENBANK/S72771