This proposal is to examine the role of regulation of gene expression by progestins, and to determine the importance of a third class of progesterone receptor protein (progesterone receptor protein C) interactions with two previously identified receptors. The progesterone receptor C may have a negative regulatory effect on receptors of the A or B class, by combining with them and then reducing their responses to progestins. The C receptor protein appears to be missing one of the two zinc fingers possessed by the A and B proteins, but contains other features of these proteins, allowing mixed dimers to form. The start site of transcription will be determined; a putative site (met 595) has been identified by the P.I., but needs to be further characterized. %%% Progesterone is a steroid hormone which binds to intracellular receptors and affects gene expression in both males and females. The mechanism of this regulation is not known. Two types of receptor have been described; this proposal deals with a third type, which may have a negative interaction with the first two types. Its production from cDNA and its interactions with the A and B class of progestin receptors will be investigated.
