PAQR5: Proteins and Enzymes

The steroid progesterone induces the resumption of maturation in oocytes via a nongenomic pathway through binding to a novel, membrane progestin receptor (mPR). This pathway inhibits adenylyl cyclase and reduces intracellular cAMP, and also activates mitogen-activated protein kinase to effect signal transduction pathways. Three distinct groups, designated alpha, beta, and gamma, comprise this gene family. While all contain 7 transmembrane domains, they show distinct distributions in reproductive, neural, kidney and intestinal tissues. These characteristics separate them from nuclear progestin receptors, and instead imply similarity to G-protein coupled receptors.