HEAT-STRESS AFFECTS THE GLUCOCORTICOID RECEPTOR INTERACTION WITH HEAT-SHOCK-PROTEIN HSP70 IN THE RAT-LIVER

The association of glucocorticoid hormones receptor (GR) with heat sho ck protein Hsp70 in the liver cytosol of rats exposed to 41 degrees C whole body hyperthermic stress was examined by quantitative immunoblot ting of the two proteins within immunopurified untransformed GR multip rotein complexes. The presence of Hsp70 in the rat liver GR heterocomp lexes was confirmed, and 2-fold increase in the Hsp70 relative to the steroid binding protein content within the complexes was recorded 2 an d 12 h after the stress. This increase exceeded the stress-induced ele vation in the total cytoplasmic Hsp70 level, but could not be seen 24 h after the stress, when cytoplasmic Hsp70 returned to basal level. Th e results suggest that hyperthermic stress alters the composition of t he rat liver untransformed GR heterocomplexes increasing the Hsp70 sha re.