Ammonium sulfate precipitation of the glucocorticoid receptor from rat liver

The transformed glucocorticoid receptor (GR) from rat liver precipitated at 30% saturation of ammonium sulfate and sedimented at 4.3 S on glycerol gradient centrifugation, whereas the nontransformed GR precipitated at higher concentrations of ammonium sulfate (40-50% saturation) and sedimented at 8.6 S on a gradient. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that heat shock protein 90 (hsp 90) precipitated at 40-50% saturation of ammonium sulfate. Moreover, hsp 90 and the nontransformed GR were eluted from DEAE high performance ion-exchange chromatography at similar salt concentrations (0.22-0.23 M NaCl), whereas the transformed GR was eluted at 0.1 M NaCl. Therefore, hsp 90 seems to be responsible for the surface charge characteristics of the nontransformed GR.