5-trans PGE2 occurs naturally in some gorgonian corals and is a common impurity in commercial lots of PGE1. It is 18 times more potent than PGE2 in activating adenylate cyclase in NCB-20 cell homogenates. 5-trans PGE2 accelerates fibrinolysis by enhancing plasminogen activation mediated by tissue-type plasminogen activator. It also inhibits platelet aggregation in human PRP with an IC50 of 180 nM.