プロスタグランジンE₂合成酵素

抄録

Prostaglandin E synthase (PGES) catalyzes isomerization of PGH₂to PGE₂which exhibits potent and various biological activities. Here we report the molecular identification of two distinct glutathione-dependent PGESs, the terminal PGE₂-biosynthetic enzymes of the cyclooxygenase (COX) pathway. These PGESs exhibit unique functional coupling with two upstream COX isozymes, COX-1 and COX-2. Cytosolic PGES (cPGES), known as p 23, is constitutively and ubiquitously expressed and predominantly converts COX-1-derived PGH₂to PGE₂. Microsomal PGES (mPGES), identical to MGST 1-L 1, is an inducible perinuclear enzyme that is functionally linked with COX-2 in marked preference to COX-1. Increased supply of arachidonic acid by explosive activation of cytosolic phospholipase A₂allows COX-1 to be coupled with mPGES.