Review Article Thromboxane A2 Receptor: Biology and Function of a Peculiar Receptor that Remains Resistant for Therapeutic Targeting

While blood platelets express several G-protein-coupled receptors (GPCRs) that play pivotal roles in their activation, several diseases, for example thrombotic disorders, may develop if these receptors are inappropriately activated. Thus, these receptors have been the subject of investigations to design therapeutic interventions for managing multiple thrombosis-based disease states. One such GPCR, the thromboxane A2 receptor (TPR), remains resistant to such interventions. The present review provides a critical examination of the binding, structural biology, and signaling of TPRs. The review also provides a rationale for using prin-ciples of ‘‘drug rediscovery’ ’ as an alternative/viable approach for the therapeutic targeting of TPRs. To this end, it is noteworthy that many US Food and Drug Administration (FDA)–approved drugs have been found to selectively (and nonselectively) block TPR-mediated functional responses, for example platelet aggregation, as described in this review. Therefore, while none of the antagonists, thus far developed for targeting TPRs, have made it into clinical use, this peculiar receptor can be antagonized by a large number of drugs used for indications unrelated to thrombosis