MPRA: 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. mPRalpha, also designated progestin and adipoQ receptor family member VII (PAQR7), consists of an extracellular N-terminus, an intracellular C-terminus, and seven transmembrane domains. It is expressed in ovary, testis, placenta, uterus and bladder. mPRbeta, also designated progestin and adipoQ receptor family member VIII (PAQR8), consists of eight putative transmembrane regions and an intracellular N-terminus that contains a leucine-rich motif. It is a 354 amino acid protein with a molecular mass of about 40 kDa and is expressed in brain and spinal cord. Both mPRalpha and mPRbeta may be G protein-coupled receptors and may be involved in oocyte maturation.