| Abstract: | 2 estrogen binding proteins of distinct high and low affinity, previously observed in calf and rat uteri, were observed in both chicken oviductal tissue and human uterine tissue. Charcoal binding and hydroxylapatite assays were performed and data were analyzed by Scatchard plot analysis. Diethylstilbestrol was used for stimulation in assay. The 2 cytoplasmic components were specific for estrogens and had equilibrium dissociation constants of 1010 and 109M. 2 binding components of similar affinities were also detected in nuclei isolated from oviducts and uteri which had been exposed to the diethylstilbestrol. Because the 2 components have now been established in widely divergent species, the presence of 2 putative estrogen receptors should be considered commonplace and that information should be used when considering steroid hormone action on the molecular level. |
