Description
The thromboxane A2 (TxA2) receptor (TP) is a member of the G protein-coupled receptor (GPCR) superfamily which mediates TxA2-induced platelet aggregation and vasoconstriction. Dysregulation of TxA2 synthesis and function has been implicated in the pathogenesis of a number of disease states including myocardial ischemia, asthma, pregnancy-induced hypertension, and a variety of kidney diseases. TP receptors (Thromboxane A2 receptors) are widely distributed among different organ systems and localized on both cell membranes and in intracellular structures. Two isoforms of human TPs have been cloned from placenta (TPα) and endothelium (TPβ) that differ in their mechanisms and kinetics of desensitization and internalization. The TPs are linked via the Gq/G11 class of G proteins to phospholipase C (PLC), which hydrolyzes phosphoinositides to two potent second messengers: inositol 1,4,5-trisphosphate, which leads to an increase in cytoplasmic free calcium, and diacylglycerol (DAG), which activates protein kinase C (PKC).