STABILIZATION OF 8S PROGESTERONE-RECEPTOR FROM HUMAN-PROSTATE IN THE PRESENCE OF MOLYBDATE ION

Abstract

In the presence of 10 mM molybdate ion, the appearance of a [6,7-3H]-17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione- ([3H]R5020)binding moiety was detected in human prostatic cytosol which sedimented at approximately 8S in a glycerol density gradient. The specifically bound [3H]R5020 was displaced by progesterone, tiramcinolone acetonide and R5020 but not by cortisol, dihydrotestosterone, 17.beta.-estradiol or diethylstilbestrol. Specific binding of [3H]R5020 in the presence of molybdate ion saturated at 7 .times. 10-10 M (n = 64 f[femto]mol/mg of protein). The optimum concentration of molybdate ion for enhancing specific binding of [3H]R5020 was between 7 and 20 mM. Molybdate ion was also effective in stabilizing the 8S R5020-binding moiety in a preincubation for 16 h at 0.degree. C in the absence of added steroid. [These results are discussed in relation to endocrine therapy for prostatic cancer.].