PAR1 (1-6) (mouse, rat) (trifluoroacetate salt) (Synonyms: H-Ser-Phe-Phe-Leu-Arg-Asn, PAR1-AP, Proteinase-Activated Receptor 1, SFFLRN, TRAP, Thrombin Receptor Activating Peptide)

PAR1 (1-6) is a hexapeptide that corresponds to amino acid residues 1-6 of the amino terminal tethered ligand sequence of mouse and rat proteinase-activated receptor 1 (PAR1), residues 42-47 of the full-length mouse sequence, and residues 46-51 of the full-length rat sequence. PAR1 is a high-affinity thrombin receptor that induces platelet activation and deposition into thrombi as well as smooth muscle mitogenesis. Unlike thrombin, PAR1 (1-6) acts as an agonist of PAR1 in smooth muscle cells but is inactive in rodent platelets. It increases mitogenesis and the expression of the IGF-1 receptor (IGF-1R) by 47% in vascular smooth muscle cells (VSMCs), an effect that is inhibited by the thrombin inhibitor hirudin and by the protein tyrosine kinase inhibitor genistein . PAR1 (1-6) increases histamine and β-hexosaminidase release from rat peritoneal mast cells in a concentration-dependent manner, with the maximum release at a concentration of 50 µM. It also mimics the effect of thrombin, increasing swelling-activated efflux of [3H]glutamate induced by hypoosmotic medium in astrocytes in vitro when used at concentrations ranging from 5 to 10 µM.