Protease-activated receptor (PAR) (PAR)

Protease-activated receptors (PARs) are a unique subfamily of G protein-coupled receptors (GPCRs) that are activated by the proteolytic cleavage of their extracellular N-terminus [UniProt: P25116]. In human platelets, PAR1 and PAR4 are the primary isoforms responsible for mediating the effects of thrombin, the most potent activator of platelets [PubMed: 24009231]. PAR1 acts as a high-affinity receptor for thrombin, triggering rapid platelet activation and aggregation, while PAR4 serves as a low-affinity receptor that sustains the activation response [PubMed: 11560990]. These receptors play a critical role in physiological hemostasis and pathological thrombosis, making them significant targets for antiplatelet therapy [StatPearls: NBK538247]. Drugs like vorapaxar target PAR1 to reduce the risk of recurrent cardiovascular events in patients with a history of myocardial infarction or peripheral arterial disease [FDA]. Beyond thrombosis, PARs are involved in inflammatory responses and vascular remodeling, contributing to various cardiovascular and fibroproliferative diseases [PubMed: 21673214].

Other names

Platelet protease-activated receptorsThrombin receptorCoagulation factor II receptorPAR1PAR4F2RF2RL3PARs

Antagonism of the receptor's tethered ligand binding site to inhibit thrombin-induced signaling and platelet aggregation [PubMed: 24009231].