Isolation and quantification of the heat shock protein 90 alpha and beta isoforms from rat liver

Summary Heat shock protein 90 (Hsp90) is an abundant cytosolic protein. In higher eukaryotes two isoforms of Hsp90 exist, Hsp90α and Hsp90β. Hsp90 was purified from rat liver and after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a double band at about 90 kDa. The two bands were separated and identified as the Hsp90α and Hsp90β isoforms. There was no entry in the protein databases for the Hsp90α isoform from rat. Furthermore, the ratio of the two Hsp90 isoforms was determined.