Receptor for platelet activating factor, a chemotactic phospholipid mediator that possesses potent inflammatory, smooth-muscle contractile and hypotensive activity. Seems to mediate its action via a G protein that activates a phosphatidylinositol-calcium second messenger system. May be involved in the morphological and physical modifications of the oviduct and uterus during the estrus cycle and early pregnancy (By similarity). Interacts with ARRB1. Found in oviductal epithelial and stroma cells. Levels in the oviduct are raised at days 2-4 of both pregnancy and of the estrus cycle. In the endometrium, localization is predominantly to the apical borders of glandular and luminal epithelial cells. Expressed at lower levels in endometrial stromal cells. Levels in the endometrium are increased at day 20 of pregnancy (at protein level). Belongs to the G-protein coupled receptor 1 family.