In humans, thromboxane (TX) A2 signals through two TXA2receptor (TP) isoforms, TPaand TPb,thatdiverge within their carboxyl terminal cytoplasmic (C) tail regions and arise by differential splicing. The human TP gene con-tains three exons E1–E3; while E1 exclusively encodes 5¢ untranslatedregion (UTR) sequence,E2andE3 represent the main coding exons. An additional noncoding exon, E1b was identified within intron 1. Additionally, the TP gene contains twopromoters P1 andP2 located 5¢of E1 andE1b, respectively
