Prostacyclin synthase

Prostaglandin-I synthase also known as prostaglandin I2 (prostacyclin) synthase (PTGIS) or CYP8A1 is an is_associated_with::enzyme involved in is_associated_with::prostanoid biosynthesis that in humans is encoded by the PTGIS is_associated_with::gene. This enzyme belongs to the family of is_associated_with::cytochrome P450 is_associated_with::isomerases.

Function
This gene encodes a member of the is_associated_with::cytochrome P450 superfamily of is_associated_with::enzymes. The cytochrome P450 proteins are is_associated_with::monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. However, this protein is considered a member of the cytochrome P450 superfamily on the basis of sequence similarity rather than functional similarity. This is_associated_with::endoplasmic reticulum membrane protein catalyzes the conversion of prostaglandin H2 to is_associated_with::prostacyclin (prostaglandin I2), a potent vasodilator and inhibitor of is_associated_with::platelet aggregation. An imbalance of prostacyclin and its physiological antagonist thromboxane A2 contribute to the development of is_associated_with::myocardial infarction, is_associated_with::stroke, and is_associated_with::atherosclerosis.

Unlike most P450 enzymes, PGIS does not require is_associated_with::molecular oxygen (O2). Instead it uses its is_associated_with::heme cofactor to catalyze the isomerization of prostaglandin H2 to prostacyclin. Prostaglandin H2 is produced by is_associated_with::cyclooxygenase in the first committed step of is_associated_with::prostaglandin biosynthesis.

Nomenclature
The systematic name of this enzyme class is (5Z,13E)-(15S)-9alpha,11alpha-epidioxy-15-hydroxyprosta-5,13-dienoate 6-isomerase. Other names in common use include prostacyclin synthase, prostacyclin synthetase, prostagladin I2 synthetase, PGI2 synthase, PGIS, PTGIS, and PGI2 synthetase.