Prostanoids are the cyclooxygenase metabolites derived from C-20 unsaturated fatty acids (arachidonic acid) and include prostaglandin (PG) D2, PGE2, PGF2 alpha, PGI2, and thrombaxane (Tx) A2. Prostaglandin F(2-alpha) is involved in a number of physiologic processes. It serves as a potent luteolytic agent in many species, has been implicated as a modulator of intraocular pressure, and may be important in smooth muscle contraction in the uterus and elsewhere. Its effects on cells are mediated through specific interaction with prostaglandin receptors (PTGFRs, PTGF2- alpha or PF2R). Human PF2R is a 359aa (calculated mo wt of ~40kD). It has 7 putative transmembrane domains characteristic of the G protein-coupled receptors. As expected, expression studies of the cDNA in Xenopus oocytes and COS cells showed strongest binding to PGF(2- alpha). It has been , mapped the gene to 1p31.1. PF2R knockout mice are unable to deliver normal fetuses at term due to a lack of response to oxytocin. The mice