Differential Release of Estradiol from Immobilized Estrogen Receptors by p-Sec-Amylphenol: Evidence for a Functional Microheterogeneity of Estrogen Receptors

Abstract

³H-Estradiol-estrogen receptor complexes were adsorbed on a column of heparin-agarose and subjected to a gradient of increasing concentrations of p-sec-amylphenol. At least five peaks of released ³H-estradiol were observed—demonstrating the existence of subsets of heparin-immobilized receptors with different affinities for estradiol. This finding is presented as further evidence for a functional microheterogeneity among estrogen receptors. The origin of the observed differences in estrogen receptors and possible relevance of the findings to receptor-mediated responses are discussed.