PAR-1
PAR-1 (F2R) is the prototypical protease-activated receptor, a GPCR that is irreversibly activated when thrombin cleaves its extracellular N-terminus, unmasking a tethered ligand that folds back into the receptor's own binding site. It is expressed on platelets, endothelial cells, smooth muscle and neurons, coupling mainly to Gq, G12/13 and Gi to drive platelet aggregation, vascular permeability and inflammatory signaling. Beyond coagulation, PAR-1 participates in tissue repair, fibrosis and tumor progression. The antiplatelet drug vorapaxar is a PAR-1 antagonist. Recombinant PAR-1 and agonist peptides enable studies of tethered-ligand activation and antithrombotic drug discovery.
