Proteinase activated receptor 4 (PAR4)

Proteinase activated receptor 4 is a member of the protease-activated receptor family, classified as a G protein-coupled receptor with seven transmembrane domains[1][8][9]. Unlike other PARs, PAR4 is primarily activated by high concentrations of thrombin, which cleaves its extracellular N-terminal domain to expose a tethered ligand sequence that triggers intracellular signaling. PAR4 couples largely to Gq and G12/13 G-proteins but not to Gi, differentiating its signaling from related receptors[1][5]. Its expression is concentrated in platelets (as a backup to PAR1 for thrombin-induced activation) and in various endothelial and neuronal tissues at lower levels, but with high functional potency[3][6]. PAR4 is implicated in the pathophysiology of arterial thrombosis, myocardial infarction, inflammatory responses, and joint pain. Therapeutic antagonism of PAR4 is being investigated to reduce thrombotic risk and inflammation with fewer bleeding complications than other antiplatelet strategies[2][4][9]. Specific small-molecule and peptide antagonists (such as BMS-986120, BMS-986141, and P4pal10) have demonstrated selective inhibition of PAR4 function in preclinical models, supporting its druggability and safety profile as a \"minimalistic\" receptor with unique trafficking and activation mechanisms[4][6][9].

Other names

Protease-activated receptor 4Thrombin receptor PAR4F2RL3

Competitive antagonism (direct inhibition of PAR4, blocking thrombin-mediated activation); Allosteric modulation (pepducins disrupt intracellular signaling); Preventing receptor cleavage or tethered ligand exposure