Localization of cyclo-oxygenase and thromboxane synthetase in human platelet intracellular membranes.
Platelet mixed membrane fractions can be separated into discrete vesicle subpopulations of surface and intracellular origin. Intracellular membrane vesicles are the predominant site of phospholipid-modifying enzymes that liberate arachidonic acid. We report the selective enrichment in intracellular membranes of cyclo-oxygenase and thromboxane synthetase activities. Surface membrane fractions show no such enrichment. These results suggest that a sequence of activities leading to the biosynthesis of thromboxane from arachidonate is associated with the intracellular membrane elements known as dense tubular membranes.
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood; D001792:Blood Platelets / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000201:enzymology; D010088:Oxidoreductases / Q000097:blood*; D011451:Prostaglandin-Endoperoxide Synthases / Q000097:blood*; D013347:Subcellular Fractions / Q000201:enzymology; D013930:Thromboxane-A Synthase / Q000097:blood*
D001095:Arachidonic Acids; D016718:Arachidonic Acid; D010088:Oxidoreductases; D011451:Prostaglandin-Endoperoxide Synthases; D013930:Thromboxane-A Synthase