COMPARTMENTATION OF PROSTAGLANDIN BIOSYNTHETIC ENZYMES

摘要

Prostaglandin endoperoxide H synthase (PGHS) catalyzes the committed step in the formation of prostaglandins and thromboxanes. There are two PGHS isozymes called PGHS-1 and PGHS-2. Both enzymes catalyze formation of PGH2 from arachidonate. The enzymes are similar structurally and have similar kinetic properties. Moreover, both isoenzymes are inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs). PGHS-1 and PGHS-2 are encoded by different genes. In general, PGHS-1 can be viewed as a constitutive enzyme whose expression appears to be regulated developmentally. PGHS-2 is an inducible enzyme which, with a few exceptions, is expressed transiently in response to growth factors, tumor promoters, or cytokines. Here we develop the concept that PGHS-1 and PGHS-2 function as part of two independent prostanoid biosynthetic systems.