Thromboxane A2 receptor (TPα) (TPα)

Thromboxane A2 receptor TPα is a G protein-coupled receptor encoded by the TBXA2R gene located on chromosome 19p13.3[1][5]. It is the α isoform resulting from alternative splicing of TBXA2R, differing from TPβ by a shorter cytoplasmic tail (343 vs. 407 amino acids)[1][5]. TPα is abundantly expressed in platelets, vascular smooth muscle, and endothelial cells, and is pivotal in hemostasis, platelet activation, and aggregation[1][3][5]. Upon activation by its primary ligand, thromboxane A2 (TXA2)—a short-lived eicosanoid produced by activated platelets—TPα initiates intracellular signaling via heterotrimeric G proteins (mainly Gq/G11), leading to platelet shape change, degranulation, aggregation, and vasoconstriction[1][3][5]. TPα is considered a prothrombotic receptor, with overactivity implicated in cardiovascular and cerebrovascular diseases, and its inhibition is a therapeutic strategy in cardiovascular disease[4][5]. Besides TXA2, TPα can also be activated by other eicosanoids (PGH2, PGF2α)[5]. Genetic and pharmacological studies in animal models demonstrate that TPα is essential for stable clot formation, and its blockade or deficiency results in impaired hemostasis and increased bleeding tendency[5]. In the vasculature, sustained TPα activation contributes to endothelial dysfunction, hypertension, and microvascular rarefaction[4]. TPα is thus a validated pharmacological target for antiplatelet and antithrombotic therapies, but its inhibition must be carefully balanced against bleeding risk.

Other names

TXA2 receptor αTP receptor αProstanoid TP receptor αThromboxane receptor αTXA2RTP-αTXA2Rα

Inhibition of TPα signaling reduces platelet activation, aggregation, and vasoconstriction; Antagonists competitively or non-competitively block receptor activation; Aspirin inhibits upstream TXA2 synthesis by irreversibly inhibiting cyclooxygenase-1 (COX-1)[2]; TPα primarily couples to Gq/G11, activating phospholipase C, increasing intracellular calcium, and inducing cell contraction; May also couple to G12/13 and Gs in some cell types[5][7].