title: Synthetic peptides demonstrate RGD-independent platelet glycoprotein IIb/IIIa recognition site in cell binding domain of human fibronectin.
abstract: Fibronectin binds to platelet membrane glycoprotein (GP) IIb/IIIa in both an Arg-Gly-Asp (RGD)-dependent and -independent manner. The identification of an RGD-independent binding domain(s) that interacts with GPIIb/IIIa may be the key to understand the mechanism of thrombus formation. A recombinant fibronectin fragment containing the residues from Ile1359 to Ser1436 (lacking the RGD sequence) had been shown to bind to GPIIb/IIIa in a divalent cation- and activation-dependent manner. To identify a minimal peptide ligand that participates in the recognition of GPIIb/IIIa, we synthesized peptides extending this region, which consist of 12 amino acid residues in length and overlapping by six amino acids. We obtained evidence that two 12-residue peptide sequences from this region (residues 1371-1382 and 1377-1388) inhibit fibronectin binding to GPIIb/IIIa by interacting directly with this receptor, with IC50s of 95 +/- 16 and 104 +/- 19 microM, respectively. These peptides inhibited the binding of fibrinogen to GPIIb/IIIa, as well as ADP-induced platelet aggregation. These results indicate that an RGD-independent GPIIb/IIIa binding site in the cell binding domain of fibronectin was localized within the residues His1377-Ile1382.
authors.affiliation: First Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Mohri
authors.forename: J
authors.initials: J
authors.lastname: Tanabe
authors.forename: K
authors.initials: K
authors.lastname: Katoh
authors.forename: T
authors.initials: T
authors.lastname: Okubo
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism; D005353:Fibronectins / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D009842:Oligopeptides; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; D000244:Adenosine Diphosphate; C047981:arginyl-glycyl-aspartic acid; D005340:Fibrinogen