Activation and changes in the sedimentation properties of rat liver glucocorticoid receptor.
The glucocorticoid receptor in rat liver cytosol was studied by sucrose gradient sedimentation, DEAE-Sephadex A-50 column chromatography and DNA-cellulose binding in order to assign specific hydrodynamic properties to both the unactivated and the activated glucocorticoid--receptor complex with [3H]-dexamethasone. Activation was effected by heat, NaCl (0.4 M) or KSCN (0.1 M) treatment. The state of activation was judged by both DNA-cellulose binding and DEAE-Sephadex A-50 anion exchange chromatography. In isotonic phosphate buffer, unactivated and activated glucocorticoid--receptor complex sedimented as a 5 S and a 4 S peak, respectively. This 5 S-4 S transformation was blocked by sodium molybdate. In hypotonic phosphate buffer, both the unactivated and the activated glucocorticoid--receptor complex assumed higher s values due to aggregation. The activated complex (4 S) yielded aggregates of 5-6 S in a reversible manner, neither complex being affected by sodium molybdate. The unactivated complex was shown to assume two distinct aggregation states of 6 S and 8-9 S, which yielded a 10-11 S heavy aggregate upon addition of molybdate. This effect on the unactivated glucocorticoid--receptor complex was readily reversed by removing the molybdate. Aggregation at low ionic strength was promoted by a low mol. wt. component(s), separated from cytosol by gel filtration through Sephadex G-10. The state of aggregation had no pronounced effect on the DNA binding properties of the activated forms or on the sensitivity of the unactivated forms to molybdate.
D000818:Animals; D002499:Centrifugation, Density Gradient; D003600:Cytosol / Q000032:analysis*; D004247:DNA / Q000378:metabolism*; D003907:Dexamethasone / Q000378:metabolism; D006358:Hot Temperature; D008099:Liver / Q000032:analysis*; D008297:Male; D008982:Molybdenum / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D013861:Thiocyanates / Q000494:pharmacology
D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D013861:Thiocyanates; D012965:Sodium Chloride; D003907:Dexamethasone; D008982:Molybdenum; D004247:DNA; C024687:sodium molybdate(VI); C009941:potassium thiocyanate