Protein components of the nonactivated glucocorticoid receptor.
The nonactivated glucocorticoid receptor (Mr approximately 350,000) of WEHI-7 mouse lymphoma cells was investigated with respect to the stoichiometry of protein subunits. Cross-linking patterns obtained by affinity labeling and denaturing gel electrophoresis revealed a heterotetramer consisting of one receptor polypeptide in association with two 90- and one approximately 50-kDa subunits. The receptor stabilized by molybdate, disulfide bond formation, or chemical cross-linking was purified roughly 6000-fold by immunoaffinity chromatography and analyzed by gel electrophoresis and immunoblotting. The 90-kDa component was consistently detected in a 2:1 ratio with respect to the receptor polypeptide and was identified as the 90-kDa heat shock protein, hsp90. A 70-kDa heat shock protein was found in both stabilized and nonstabilized receptors and bound to the immunomatrix independent of receptor. The additional receptor subunit was unequivocally identified as the 59-kDa protein previously described (Tai, P.-K. K., Maeda, Y., Nakao, K., Wakim, N. G., Duhring, J. L., and Faber, L. E. (1986) Biochemistry 25, 5269-5275). This component was found only in complexes cross-linked via amino groups. It was removed from the molybdate-stabilized receptor under our purification conditions, thus leaving behind a trimer composed of the receptor polypeptide and two molecules of hsp90. In the absence of hormone, the receptor had the same subunit composition as in its presence.
Rexin
M
M
Institut für Biologische Chemie, Universität Heidelberg, Germany.
Busch
W
W
Gehring
U
U
D000818:Animals; D015153:Blotting, Western; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000032:analysis; D051379:Mice; D011506:Proteins / Q000032:analysis; D011965:Receptors, Glucocorticoid / Q000737:chemistry*; D014407:Tumor Cells, Cultured
D003432:Cross-Linking Reagents; D006360:Heat-Shock Proteins; D011506:Proteins; D011965:Receptors, Glucocorticoid