Estramustine-binding protein in rat and human prostate.

Estramustine phosphate, a nor-nitrogen mustard carbamate derivative of oestradiol-17 beta-phosphate, labelled with tritium in the oestradiol moiety, caused a higher concentration of radioactivity in rat prostate than did tritiated oestradiol-17 beta-phosphate or oestradiol-17 beta. Further studies in rat prostate demonstrated a protein that binds etramustine, the dephosphorylated metabolite of estramustine phosphate. The physical and chemical properties of this protein have been investigated, as has its presence in different organs of the rat and other species, including man. The finding of estramustine- binding protein in the human prostate gave rise to speculations concerning possible significance of estramustine phosphate's mechanism of action. The initial studies on estramustine-binding protein in rat and human prostate are briefly presented.