Thromboxane A(2) 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 physiological actions of thromboxane A (2) (TXA(2)) and its related metabolites. These molecular insights have bee n greatly expedited by the molecular cloning and characterization of a cDNA for the human TXA(2) receptor, now termed the T Prostanoid or TP receptor, from a megakaryocytic/placental cDNA library in 1991, and later through th e 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 s pecies thus far investigated, is unclear, but points to potential species-s pecific physiological differences. In this review, I will describe some rec ent advances in the research field of TXA(2)/TP receptor signalling, focusi ng particularly on studies pertaining to the human TP receptor isoforms.