The role of estrophilin in estrogen action.

The role of estrophilin in estrogen action was reviewed. The interaction of uterine cells with estradiol involves the association of estradiol with estrophilin followed by temperature-dependent translocation of the resulting complex to the nucleus. The steroid binding unit of estrophilin undergoes an alteration (receptor transformation) that is recognized by an increase in its sedimentation rate and by its ability to bind to isolated uterine nuclei or chromatin and to alleviate a tissue specific deficiency in the ribonuclei acid (RNA) synthesizing capacity. The estrophilin complex influence on RNA synthesis in isolated nuclei shows the same quantitative, qualitative and tissue specificity characteristics as evoked by the administration of estradiol in vivo. It was concluded that receptor transformation is an important step in estrogen action and that a major role of the hormone is to induce conversion of the native estrophilin to a biochemically functional form.