F2R, also known as protease-activated receptor 1 (PAR1), is a G protein-coupled receptor (GPCR) activated by proteolytic cleavage. It plays critical roles in coagulation, inflammation, and cellular responses to injury. PAR1 is primarily activated by thrombin, a serine protease central to blood clotting. Thrombin cleaves PAR1’s N-terminal exodomain, unmasking a tethered ligand that binds intramolecularly to trigger downstream signaling. This receptor is expressed on platelets, endothelial cells, smooth muscle cells, and various cancer cells, influencing processes like platelet aggregation, vascular permeability, and tumor metastasis.
F2R antibodies are tools developed to study or modulate PAR1 activity. They include antagonistic antibodies that block thrombin-induced signaling by binding to PAR1’s thrombin cleavage site or ligand-binding regions, thereby inhibiting platelet activation or inflammatory responses. Conversely, agonist-like antibodies can mimic PAR1 activation, aiding in mechanistic studies. Therapeutic applications of F2R antibodies are explored in thrombotic disorders, atherosclerosis, and cancer, where PAR1 overexpression correlates with poor prognosis. For instance, PAR1 inhibition may reduce thrombosis risk without increasing bleeding, a limitation of conventional anticoagulants. Challenges include ensuring specificity to avoid off-target effects and optimizing bioavailability. Recent research also highlights PAR1’s role in COVID-19-related coagulopathy, spurring interest in F2R-targeted therapies. Overall, F2R antibodies represent versatile biological tools with translational potential in cardiovascular and oncological diseases.