Estrogen receptors in the chick oviduct

An estradiol binding component has been identified in the cytoplasmic fraction of the immature chick oviduct. The method used to resolve this receptor differed from the standard sucrose gradient centrifugation approach in that tritiated hormone was present throughout the sucrose gradient. This modification was necessary to preserve the hormone complex during centrifugation. Under these conditions, an similar to 8 S binding component was demonstrated which underwent dissociation to a similar to 5 S component in high ionic strength medium. Binding specificity determinations revealed that this receptor preferentially bound estrogens. Quantitative binding analysis showed that a limited class of binding sites was present with a dissociation constant (K-d) for estradiol of similar to 8.6 times 10-10M. These properties indicate that this binding component may function as a biologic receptor for estrogens in the oviduct.