The major thrust of the proposed studies is essentially two fold: (1) the isolation and characterization of the hCG/hLH receptor from superovulated rat ovaries and (2) the structure and function relationships in gonadotropins. The studies on hCG/hLH receptor will include (a) partial amino acid sequencing of the receptor subunits by a gas phase sequenator with the objective of using the sequence information to synthesize cDNA probes for the isolation and cloning of the receptor gene, (b) the determination of molecular properties of the receptor such as phosphorylation, glycosylation and acylation, and (c) production of monoclonal and polyclonal antibodies against the receptor. Structure and function studies will primarily focus on the role of carbohydrates in the function of gonadotropins. The cellular and molecular mechanisms of carbohydrate action in the hormonal signal transduction from hormone-receptor complex to the adenylate cyclase system and to the subsequent biological events will be studied. The effect of carbohydrate of the ligand on the induction of specific conformational change in the receptor, its desensitization and internalization will be investigated. The role of carbohydrate in eCG will also be studied and the effect of its removal on both its LH and FSH activities will be determined. The hCG specific antigenic site in DS5-hCG-Beta, a specific antigen obtained by the controlled reduction and alkylation of hCG-Beta, will be identified. This will be further confirmed by using synthetic peptide representing the hCG specific antigenic site and studying the inhibition of binding of DS5-hCG-Beta to its antibody by the peptide. Finally, the heterogeneity of carbohydrates in hCG, oLH and disease state hCG will be investigated by the newly developed thin layer chromatographic system. These basic studies on the receptor and hormone function would help in developing newer approaches to fertility regulation. Furthermore, the monoclonal antibodies to hCG-Alpha and hCG-Beta have potential in cancer diagnosis.
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