Thromboxane A2 receptor is a member of the G protein-coupled receptor superfamily. It performs an essential role in hemostasis by interacting with thromboxane A2 to induce platelet aggregation. Thromboxane A2 is an arachidonic acid metabolite produced by the action of thromboxane synthase on prostaglandin endoperoxide H(2) (PGH(2)), which results from the enzymatic transformation of arachidonic acid by the cyclooxygenases (COX-1 and COX-2). In humans Thromboxane A2 signals through two distinct