Hsp90 is a molecular chaperone essential to the folding, activation and maturation of small number of distinct client proteins. It is involved in regulating cell growth and differentiation. Levels of Hsp90 increase in cancer cells, therefore, it is of critical importance to cancer-related phenotypes. Hsp90 client proteins bind to the multi-component Hsp90 chaperone complex. Results from Rotenberg Laboratory show that Hsp90 and PKCα co-immunoprecipitate, suggesting a functional relationship between Hsp90 and PKCα. We will use Saccharomyces as a model system to explore the possibility that PKCα is an Hsp90 client. Bovine PKCα will be expressed in Saccharomyces strains carrying defects in the Hsp90/Hsp70 chaperone machinery and its impact on PKCα catalytic function will be determined. The proposed work will look at the expression levels of 3HA-tagged PKCα in wild-type as well as various Hsp90 mutants. We will also test to see if bovine PKCα co-immunoprecipitates with Hsp90 and Hsp70 complex. PKCα will be partially purified by immunoprecipitation and its kinase activity monitored by an in vitro assay using a known PKCα substrate, MARCKS protein.