Estradiol- and estriol-binding in human benign prostatic hyperplasia.

Binding of the natural estrogens, estradiol and estriol, was investigated, in 34 samples of human benign prostatic hypertrophy (BPH) tissue, using Scatchard analysis and agar gel electrophoresis. Saturation binding analysis using a wide range of concentrations of both ligands resulted in curvilinear Scatchard plots. This confirmed the presence of two binding forms for estradiol: a true estrogen receptor, and a protein with lower affinity and higher capacity. Both binding species were also demonstrated and quantified with estriol. The electrophoretic process, after incubation at low and high ligand concentrations also resulted in separation, for both estrogens, of two binding peaks. They are probably two distinct forms of the low affinity, high capacity binding measured by Scatchard. The procedure used in our laboratory was not able to provide accurate determination of the concentrations of these binding forms. Possible modifications to alleviate these drawbacks are discussed.