Coagulation factor II receptor (PAR-1) (PAR-1)

Coagulation factor II receptor (PAR-1) is the primary molecular mediator of thrombin's effects on human platelets (UniProt P25106). It belongs to the G protein-coupled receptor (GPCR) family and is unique because it is activated through proteolytic cleavage of its extracellular N-terminus by thrombin (PubMed: 22133311). This cleavage exposes a tethered ligand that intramolecularly binds and activates the receptor, triggering intracellular signaling cascades that lead to platelet shape change, granule release, and aggregation. In the context of cardiovascular disease, overactivation of PAR-1 contributes to arterial thrombosis, leading to conditions such as myocardial infarction and ischemic stroke (PubMed: 24509671). Therapeutic targeting of PAR-1, primarily through antagonists like Vorapaxar, aims to reduce thrombotic events by inhibiting thrombin-induced platelet activation without significantly affecting the primary hemostatic response mediated by ADP or collagen (FDA: Zontivity Label). However, the clinical use of PAR-1 inhibitors is limited by a significant risk of major bleeding, particularly intracranial hemorrhage. Research also suggests PAR-1 plays roles in inflammation and vascular remodeling beyond simple hemostasis, making it a complex target in vascular biology.

Other names

Protease-activated receptor 1Thrombin receptorF2RTRPAR1

Competitive antagonism of the protease-activated receptor 1 (PAR-1), preventing the binding of the thrombin-cleaved tethered ligand and subsequent platelet activation.