Proteinase-activated receptor 4 (PAR-4) is a receptor for activated thrombin or trypsin. PAR-4 is coupled to G proteins that stimulate phosphoinositide hydrolysis. PAR-4 plays a role in platelet activation. PAR-4 is widely expressed in tissues, but is not expressed in brain, kidney, spinal cord and peripheral blood leukocytes.The synthetic peptide used to raise the antibody Cat. No. 251564 is selected from a sequence within the C-term region of human PAR-4. For blocking experiments, a 10 to 100 fold molar excess to antibody is recommended.