Concomitant preparative isolation of calmodulin and heat shock protein (hsp90) from bovine testes

We have described a convenient procedure for isolating large amounts of both calmodulin and the 90-kDa heat shock protein (hsp90) from bovine testes. These two proteins coeluted from phenyl-Sepharose during calcium-dependent hydrophobic interaction chromatography. The hsp90 was separated from calmodulin by gel filtration, purified by reverse-phase HPLC or lectin affinity chromatography, and identified by N-terminal amino acid sequence and immunoblotting with hsp90-specific monoclonal antibody. The N-terminus of bovine hsp90 shared 93% amino acid identity with the murine alpha-isoform of hsp90. A third major testes protein of 97 kDa was also isolated with this protocol and was found to be homologous to the 94-kDa glucose-regulated protein.