Regulation of Expression and the Functional Role of Cyclooxygenase-2

Cyclooxygenase (Cox), also known as Prostaglandin H Synthase (E.C.1. 14.99.1) is a rate limiting enzyme in a synthesis of prostanoids. Once the cellular phospholipase A2 has released arachidonic acid from membrane phospholipids, the Cox enzyme oxidizes arachidonic acid to PGG2 by the cyclooxygenase activity and then reduces PGG2 to PGH2 by the peroxidase activity. The PGH2 is converted to various bioactive prostanoids by tissue specific isomerases (1). Cox enzyme is an integral membrane protein located in endoplasmic reticulum and nuclear membrane (2). It is irreversibly self-inactivated after a limited amount of catalysis and then rapidly degraded by proteases (3).