DESCRIPTION (provided by applicant): The goal of the proposed study is to identify and characterize the oocyte maturation hormone receptor in the starfish, Patina miniata. This model system offers significant advantages over others and some aspects may be shared with mammalian oocytes. The proposed work is designed to identify and characterize this receptor using unique homology based and functional expression cloning based approaches in tandem to identify and clone candidate cDNA(s) encoding the receptor for the maturation-inducing hormone, 1-methyladenine (1- MA). Successful identification of the 1-MA receptor using these novel strategies would represent the first definitive description of a maturation-inducing hormone receptor in any species and provide proof of concept for the strategy to be used for the identification of maturation hormone receptors in other species, including mammals. Several candidate cDNAs already have been isolated; these and additional candidates will be subjected to further functional studies to confirm identity and tests for necessity in oocyte maturation will be conducted. Eventually, studies will be conducted that are designed to elucidate the details of the molecular mechanism of signal transduction during oocyte maturation.