Protease-activated receptor 3 (PAR3)

Protease activated receptor 3 (PAR3) is a member of the G protein-coupled protease activated receptors subfamily that mediates cellular responses to serine proteases such as thrombin. Unlike some other members of the family, human PAR3 can mediate phosphoinositide hydrolysis upon activation by thrombin but appears less capable than others at directly coupling with G-proteins due to lacking certain cytoplasmic domains. Instead, it often functions as an allosteric modulator—forming heterodimers with other receptors like PAR1—to regulate their sensitivity and downstream signaling specificity via selective coupling with different G proteins such as Gα13. It plays important roles in regulating platelet function, endothelial cell permeability, thrombosis risk, vascular inflammation, and possibly tissue repair mechanisms. Its unique regulatory properties make it an attractive potential therapeutic target for conditions involving abnormal clotting or inflammatory responses.[1][2][4]

Other names

PAR3Thrombin receptor (context-dependent; more commonly used for PAR1 but sometimes applied to other PARs)F2RL2 (gene symbol)

Drugs targeting this molecule would likely act by inhibiting its activation by proteases such as thrombin or by blocking downstream signal transduction through G-protein coupling. Inhibitors could prevent dimerization with other receptors like PAR1 or block allosteric modulation of related pathways involved in endothelial permeability and platelet function[1].