The tetrapeptide analogue of the cell attachment site of fibronectin inhibits platelet aggregation and fibrinogen binding to activated platelets

• Published in: The Journal of biological chemistry Vol. 260; no. 22; pp. 11891 - 11894
• Main Authors: Gartner, T K, Bennett, J S
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05.10.1985; American Society for Biochemistry and Molecular Biology
• Subjects: Adenosine Diphosphate - pharmacology; Amino Acid Sequence; Biological and medical sciences; Blood coagulation. Blood cells; Blood Platelets - drug effects; Blood Platelets - metabolism; Fibrinogen - metabolism; Fibronectins - physiology; Fundamental and applied biological sciences. Psychology; Humans; Kinetics; Molecular and cellular biology; Oligopeptides - pharmacology; Platelet; Platelet Aggregation - drug effects; Platelet Membrane Glycoproteins; Receptors, Cell Surface - drug effects; Receptors, Cell Surface - metabolism; Serotonin - blood; Aggregation; Human; Membrane receptor; Platelet; Peptides; Fibrinogen; Molecular interaction; Activation; Glycoproteins; Binding site; Inhibition; Fibronectin
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)38962-7

Fibrinogen binding to receptors on activated platelets is a prerequisite for platelet aggregation. However, the regions of fibrinogen interacting with these receptors have not been completely characterized. Fibronectin also binds to platelet fibrinogen receptors. Moreover, the amino acid sequence Arg-Gly-Asp-Ser, corresponding to the cell attachment site of fibronectin, is located near the carboxyl-terminal region of the alpha-chain of fibrinogen. We have examined the ability of this tetrapeptide to inhibit platelet aggregation and fibrinogen binding to activated platelets. Arg-Gly-Asp-Ser, but not the peptide Arg-Gly-Tyr-Ser-Leu-Gly, inhibited platelet aggregation stimulated by ADP, collagen, and gamma-thrombin without inhibiting platelet shape change or secretion. At a concentration of 60-80 microM, Arg-Gly-Asp-Ser inhibited the aggregation of ADP-stimulated gel-filtered platelets approximately equal to 50%. Arg-Gly-Asp-Ser, but not Arg-Gly-Tyr-Ser-Leu-Gly, also inhibited fibrinogen binding to ADP-stimulated platelets. This inhibition was competitive with a Ki of approximately equal to 25 microM but was incomplete even at higher tetrapeptide concentrations, indicating that Arg-Gly-Asp-Ser is a partial competitive inhibitor of fibrinogen binding. These data suggest that a region near the carboxyl-terminus of the alpha-chain of fibrinogen interacts with the fibrinogen receptor on activated platelets. The data also support the concept that the sequence Arg-Gly-Asp-Ser has been conserved for use in a variety of cellular adhesive processes.