title: Localization of cyclo-oxygenase and thromboxane synthetase in human platelet intracellular membranes.
abstract: 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.
mesh_terms: 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*
chemical_list: D001095:Arachidonic Acids; D016718:Arachidonic Acid; D010088:Oxidoreductases; D011451:Prostaglandin-Endoperoxide Synthases; D013930:Thromboxane-A Synthase