Thromboxane A2 signalling in humans : a ‘tail’ of two receptors

Since its discovery in 1975, we now have a wealth of knowledge relating to the biochemical, pharmacological and physiologic actions of thromboxane (TX) A2 and its related metabolites. These molecular insights have been greatly expedited by the molecular cloning and characterisation of a complementary (c) DNA for the human TXA receptor, now termed T Prostanoid or TP receptor, from a megakaryocytic / placental cDNA library in 1991 and later through the discovery of a cDNA encoding a second isoform of the human TP receptor in 1994. The requirement for two TP receptors in primates, but not in other species thus far investigated, is unclear but points to potential species-specific physiologic differences. In this review, I will describe some recent advances in the research field of TXA2/TP receptor signalling, focussing particularly on studies pertaining to the human TP receptor isoforms.