Antibodies to Estrogen, Progesterone, Glucocorticoid, Vitamin D Receptors and Autoantibodies to Androgen Receptor

Abstract

Steroid hormones regulate cell function by interacting with specific receptor proteins (Gorski et al., 1968; Jensen and DeSombre, 1972; O’Malley and Means, 1974; Liao, 1975; Muldoon, 1980; Schrader, et al., 1981; Schmidt and Litwack, 1982; Jensen et al., 1982; Ringold, 1985). Specific receptors for a number of steroid hormones have been purified (O’Malley and Schrader, 1976; Govindan, 1979; Kuhn et al., 1975; Pike et al., 1982; Jensen et al., 1982). Most of our present knowledge of steroid receptors and their action in target cells has been derived on the basis of receptor binding to radiolabeled steroid. The labeled ligand technique has certain inherent limitations: (1) The labeled steroid can only bind to unoccupied binding sites on the receptor protein; (2) it cannot interact with inactive or nonfunctional receptor proteins that may exist under certain physiological and pathological conditions; (3) other steroid binding proteins present in the target cell interfere with the ligand-binding assay. These difficulties have led to the search for a better alternative for identification and quantification of steroid receptors such as the immunochemical approach. Preparation of monospecific antibody generally requires purified antigen, and steroid receptors constitute only a minor component of cellular proteins. Therefore, purification of steroid receptors to homogeneity has always been fraught with insurmountable difficulties.