Sodium molybdate converts the RNA-associated transformed, oligomeric form of the glucocorticoid receptor into the transformed, monomeric form.
The glucocorticoid receptor from rat liver cytosol prepared in 2 ml buffer/g tissue sedimented at approximately 10 S in low salt density gradient centrifugation without molybdate. When the receptor was heated at 25 degrees C, both approximately 10 S and approximately 7 S forms were seen in low salt gradient. The approximately 10 S form was not capable of binding to DNA-cellulose and was stabilized by sodium molybdate, namely it corresponded to untransformed receptor. The approximately 7 S form was capable of binding to DNA-cellulose and regarded as transformed receptor. On the other hand, partially-purified transformed receptor labeled with [3H]dexamethasone-21-mesylate sedimented at approximately 5 S, which migrated as a approximately 94 kDa species in SDS-polyacrylamide gel electrophoresis. The reconstitution analysis of this partially-purified approximately 5 S receptor and liver cytosol, showed the shift to approximately 7 S form. RNase A or T1 converted approximately 7 S transformed form into approximately 5 S but it did not affect approximately 10 S untransformed form. 5-20 mM sodium molybdate also shifted approximately 7 S to approximately 5 S. These results indicate that the approximately 7 S transformed form of the glucocorticoid receptor observed in low salt conditions might be an oligomer, probably including both approximately 5 S steroid-binding component and RNA/ribonucleoprotein, and that molybdate dissociates these interactions in a specific manner.
D000315:Adrenalectomy; D000818:Animals; D003600:Cytosol / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D046911:Macromolecular Substances; D008297:Male; D008970:Molecular Weight; D008982:Molybdenum / Q000494:pharmacology*; D012313:RNA / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*
D046911:Macromolecular Substances; D011965:Receptors, Glucocorticoid; D012313:RNA; D008982:Molybdenum; C024687:sodium molybdate(VI)