Elucidation of steroid hormone receptor structure and function is necessary for understanding steroid hormone action. Such an understanding has significant clinical implications, as steroid hormones are used with increasing frequency and diversity in medical treatments (1). Evidence that a population of the rat liver glucocorticoid receptor is a glycoprotein, supported by binding of a significant fraction of the rat liver [3H]dexamethasone receptor (dex-R) to ConcanavalinA-Sepharose4B (ConA-Seph), establishes the basis for the proposed research. In light of current hypotheses of the functional and structural significance of carbohydrate moieties of glycoproteins (2,3), the glycoprotein nature of glucocorticoid receptor is significant. Our goals are: 1) to evaluate experimental conditions required for the observation of glycoprotein dexamethasone receptor form(s) and to undertake basic structural and functional characterization of these special receptor forms; and 2) to examine the macromolecular associations of glycoprotein receptor form(s) and conditions for generation of soluble receptor form(s). The first goal will be approached as follows: i) determination of experimental conditions affecting the presence, detection and separation of glycoprotein receptor forms; ii) characterization of glycoprotein receptor form(s) from crude liver preparations; iii) purification of glycoprotein receptor form(s) and characterization from more purified fractions; and iv) evaluation of the functional significance of glycosylated receptor (e.g., ability to transform or translocate into the nucleus). The second goal will involve the following studies: i) identification of the subcellular components associated with different glycoprotein receptor forms, ii) examination of the structural association of glycoprotein with macromolecular fractions; and iii) definition of the thermodynamic and kinetic parameters defining the release of soluble receptor forms from macromolecular precursor.
