Reproductive functions of the progesterone receptor

Progesterone plays a central coordinate role in regulating reproductive eve nts associated with the establishment and maintenance of pregnancy includin g ovulation, uterine and mammary gland development and tumorigenesis, and n eurobehavioral expression associated with sexual responsiveness. The effect s of progesterone are mediated by two receptor proteins (PR), termed A and B, that arise from a single gene and act as ligand-activated transcription factors to regulate the expression of reproductive target genes. Null mutat ion of both proteins in mice leads to pleiotropic reproductive abnormalitie s. This review summarizes the structure and functional properties of the PR isoforms and how functional differences between these proteins are likely to impact on the overall physiologic role of the receptor in reproductive s ystems. (J Soc Gynecol Investig 2000;7:S25-32) Copyright (C) 2000 by the So ciety for Gynecologic Investigation.