Purification and characterization of the activated mineralocorticoid receptor from rat kidney.

1. The mineralcorticoid receptor (MR) from rat kidney was purified within 8 hr by the following, successive steps: stabilization with synthetic, tritiated steroids (RU 26752 or R 5020), phosphocellulose passage, heat activation (25 degrees C), and DNA-cellulose batch elution. 2. The purified preparation was resolved as a single, 75 KDa band on SDS-PAGE electrophoresis although the exact degree of purity was difficult to assess by the charcoal assay due to denaturation. 3. The natural hormone, aldosterone, was unsuitable for receptor purification and characterization. 4. The MR purified with different ligands behaved identically during ion exchange and gel permeation analyses, suggesting post-translational modifications of the native receptor in whole cytosol that exhibits molecular heterogeneity.