Molecular chaperones have been implicated in the formation of active p60v-src tyrosine kinase. In Saccharomyces cerevisiae, expression of p60v-src causes cell death, a phenomenon that requires functional Hsp90. We show here that mutations in a member of a second class of chaperones, the yeast dnaJ homologue YDJ1, suppress the lethality caused by p60v-src. One p60v-src-resistant ydj1 mutant, ydj1-39, which has two point mutations in the highly conserved "J" domain, has reduced levels of v-src mRNA and protein. However, a ydj1 null mutant produces normal quantities of active p60v-src, indicating that Ydj1p facilitates, but is not essential for, the formation of active p60v-src. We also report p60v-src-resistance in a previously identified temperature-sensitive ydj1 mutant, ydj1-151. In this mutant, the level of p60v-src remains unaltered, but the protein is much less active in vivo. In addition, p60v-src immunoprecipitates from the ydj1-151 strain contained Hsp90 and Hsp70 in greater amounts than in wild-type strains. Ydj1 protein was also detected in p60v-src immunoprecipitates from both wild-type and ydj1-151 strains. These results indicate that Ydj1p participates in the formation of active p60v-src via molecular chaperone complexes.

• PMID: 8741842
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Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Dey B, Caplan AJ, Boschelli F

Primary Lit For

HSP82 | YDJ1

Additional Lit For

SSA1 | HSC82 | SSA2

Review For