Effect of sodium molybdate on cytosolic androgen receptors in rat prostate

The addition of 10 −2 M sodium molybdate either to the homogenization buffer or to the homogenate (immediately after the homogenization) results in higher yields of cytosolic rat prostate androgen receptor as determined with [ 3H]-17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (R1881) or [ 3H]-dihydrotestosterone (DHT) at 0°C. The increase varies between 10 and 80%, depending upon the experiments and the physiological condition of the animals. It is observed both by charcoal assay and by sucrose density gradient centrifugation. Molybdate has no effect on association constant ( K a , on sedimentation profiles on sucrose gradients, on steroid specificity and on the rate of dissociation of [ 3H]-steroid receptor complex in the presence of unlabelled ligand. Molybdate increases the stability of androgen receptor complex against physiochemical denaturation at 0°hC and thermal denaturation at 15° and 25°C. Protection afforded by molybdate appears to occur by a mechanism common to receptor protection by endogenous hormones.