Characterization and partial purification of androgen receptors from ram seminal vesicles

An androgen receptor has been demonstrated in the cytosol and in the nuclear fraction of ram seminal vesicles. The cytosol receptor was stabilized by sodium molybdate and 2 distinct [3H]methyltrienolone-binding proteins, one sedimenting at 9S and one sedimenting at 3S, could be demonstrated by sucrose-gradient centrifugation in the presence of 50 mM molybdate. The slower sedimenting form could be partially purified by ADP-sepharose chromatography. The purified receptor still sedimented at 3S after centrifugation on sucrose gradients containing either 0.6 M KCl or 50 mM molybdate. The receptor was destroyed by heating at 50 degrees C for 30 min and its complex with [3H]methyltrienolone dissociated slowly at low temperatures. The apparent equilibrium-dissociation constant (KD) for the purified receptor was: 3.8 x 10(-10) M. The relative affinities for different steroids decreased in the following sequence: 5 alpha-dihydrotestosterone greater than or equal to methyltrienolone greater than testosterone much greater than estradiol greater than R5020 greater than progesterone greater than diethylstilbestrol. The nuclear androgen receptor sedimented at 3S on sucrose gradients containing 0.6 M KCl. At pH 7.4 it behaved as an acidic protein with an electrophoretic mobility towards the anodic region of the agar gel. Because of the relatively large content of cytoplasmic and nuclear androgen receptors and the availability of large amounts of tissue the ram seminal vesicles could be a suitable source for large-scale purification of these receptors.