title: A novel peptide motif for platelet fibrinogen receptor recognition.
abstract: To develop a specific antagonist of platelet alphaIIbbeta3 using small linear peptides, we synthesized a series of hexapeptides that did not have an Arg-Gly-Asp (RGD) sequence and examined their anti-platelet activity and their specificity for alphaIIbbeta3. We found a novel motif sequence, Pro-X1-X2-X3-Asp-X4, where X1 to X4 were all L-form alpha-amino acids, which specifically inhibited aggregation of human platelets at submicromolar concentrations. The Pro residue at the N terminus was essential to the anti-platelet activity, and the acetylation of the imino group of this residue also resulted in the complete loss of the activity. The results of the binding assay using purified human platelet alphaIIbbeta3 and placental alphavbeta3 and those of the cell adhesion assay suggest that this motif peptide is highly specific for platelet alphaIIbbeta3 among other integrins. Flow cytometric studies using an fluorescein isothiocyanate-labeled RGD peptide showed that this motif peptide inhibited the binding of an RGD peptide to activated platelets, suggesting that it has the same inhibitory mode as RGD peptides. Conformational analysis of this motif peptide and an RGD-containing peptide suggests that the imino group of the Pro residue may substitute for the role of the guanidino group of the Arg residue of the RGD sequence.
authors.affiliation: Life Science Research Center, Advanced Technology Research Laboratories, Nippon Steel Corporation, 1618 Ida Nakahara-ku, Kawasaki 211, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Katada
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Muramatsu
authors.forename: Y
authors.initials: Y
authors.lastname: Takiguchi
authors.forename: T
authors.initials: T
authors.lastname: Harada
authors.forename: T
authors.initials: T
authors.lastname: Fujiyoshi
authors.forename: I
authors.initials: I
authors.lastname: Uno
mesh_terms: D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D006801:Humans; D008297:Male; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D013927:Thrombosis / Q000517:prevention & control
chemical_list: D009842:Oligopeptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex