Merck, A3227-1MG, Ala-Tyr-Pro-Gly-Lys-Phe-NH₂ trifluoroacetate salt

Ala-Tyr-Pro-Gly-Lys-Phe-NH₂ (AYPGKF- NH₂) is a selective, specific proteinase-activated receptor 4 (PAR4) agonist peptide. PAR4 is a G-protein-coupled receptor that is expressed on the surface of human platelets and is involved in the thrombin signaling pathway. Cleavage of PAR4 by the protease thrombin stimulates the receptor and results in signaling of platelet aggregation.