Progestin-binding protein in human benign prostatic hypertrophy.

Abstract

Cytosols from human benign prostatic hypertrophy contained progestin-binding components which bound to R 5020, ORG 2058 and progesterone in high affinity fashion. Most of the protein bound to R 5020 was recovered in the precipitate with 0-30% saturation of ammonium sulfate. The R 5020-binding protein showed sedimentation coefficients of 3.6S and 8.4S, and was eluted in the void volume of a Sephadex G-200 column. This protein was clearly distinguished from the dihydrotestosterone-binding protein by its precipitability by ammonium sulfate, heat stability and susceptibility to delipidization. R 5020 and ORG 2058 binding were markedly inhibited by the addition of R 1881, therefore, most of the binding to progestin in cytosols from the benign prostatic hypertrophy seems to be also the sites for R 1881. Although nuclear extract by 0.4 M KCl showed R 1881 binding, the extract did not contain the R 5020-binding protein, and this suggested that the progestin-binding protein observed in the cytosols does not seem to be the steroid receptor.