[Purification of the human prostate androgen receptor. II. Characterization of the human prostate androgen receptor].

For improved purification of human prostate androgen receptors (AR), the effect of molybdate, NaSCN and heparin on the binding capacity of human prostate cytosol AR was investigated. When 10 mM of molybdate in final concentration was added to cytosol, the increase in the maximum binding sites of AR to 3H-R1881 was approximately 60%, while the dissociation constant was rather increased. With sucrose density gradient centrifugation, the cytosol with molybdate added showed a constant peak of 8 approximately 9 S. However, cytosol not enriched with molybdate did not show any significant peak. These results constitute evidence that molybdate has a stabilizing effect of the AR. When 0.1 approximately 0.5 M of NaSCN was added to the cytosol, the dissociation as well as the association of the 3H-R1881-AR complex showed a tendency to accelerate. However, at a concentration of 0.3M and over NaSCN, the binding capacity of the AR rapidly disappeared. When the NaSCN was removed with gel filtration, the binding capacity of the AR recovered partially. The effect of NaSCN on the AR was therefore different from that on the estrogen receptors. Four mg/ml of heparin accelerated the dissociation of the 3H-R1881-AR complex. Furthermore, with the addition of 4 mg/ml of heparin, the maximum binding sites of AR decreased to 56%. The above results make it clear that molybdate, NaSCN and heparin have various effects on human prostate cytosol AR, which might be applied to the purification of AR.