Prostaglandin (PG) E2 is involved in a number of physiological and pathophysiological events in many tissues throughout the body. The biological effects of PGE2 are mediated through interaction with specific membrane-bound G-protein-coupled prostanoid EP2 receptors. There are four subtypes of the EP receptor, termed EP1, EP2, EP3 and EP4, which have been defined on the basis of their different pharmacological profiles and signal transduction pathwas.EP1 is characterized by the presence of a helical bundle consisting of seven hydrophobic transmembrane helices (TM1-TM7), which are connected through six alternating extracellular and intracellular loops. The N-terminus is located on the extracellular side of the membrane, whereas the C-terminus occupies the intracellular side
