 All of the prostanoid receptors are G protein-coupled receptors belonging to the Subfamily A14 of the rhodopsin-like receptor family except for the Prostaglandin DP2 receptor which is more closely related in amino acid sequence and functionality to chemotactic factor receptors such as the receptors for C5a and leukotriene B4.Prostanoid receptors bind and respond principally to metabolites of the straight chain polyunsaturated fatty acid (PUFA), arachidonic acid.These metabolites contain two double bonds and are named series 2 prostanoids, i.e.