Proteinase-activated receptor 2 (and) Proteinase-activated receptor 4 (PAR2 (for Proteinase-activated receptor 2); PAR4 (for Proteinase-activated receptor 4))

Proteinase-activated receptors 2 and 4 are members of the protease-activated receptor family of G protein-coupled receptors, which are activated by proteolytic cleavage of their N-terminal domains by serine proteases (e.g., trypsin for PAR2, thrombin for PAR4). PAR2 is widely involved in inflammation, immune cell signaling, cancer, obesity, and metabolic regulation, while PAR4 is best known as a key regulator of platelet activation and aggregation, working synergistically with other receptors in thrombotic processes. Both are under active investigation as therapeutic targets for inflammatory, cardiovascular, and thrombotic diseases. Their signaling mechanisms, biological functions, and regulatory pathways are structurally and mechanistically distinct, but related within the PAR family.

Other names

Coagulation factor II (thrombin) receptor-like 1F2RL1GPR11F2RL3Coagulation factor II (thrombin) receptor-like 3

For PAR2, drugs act as antagonists (block G protein-coupled signaling), agonists (activate signaling), or biased agonists (selectively activate specific pathways). For PAR4, inhibitors block platelet activation and aggregation; agonists mimic thrombin cleavage-induced activation.