Antibodies to GPIIb alpha (300-312) inhibit Fg binding, clot retraction, and platelet adhesion to multiple ligands.
We previously reported that a peptide with the sequence Gly-Ala-Pro-Leu (GAPL) found as residues 309-312 in glycoprotein IIb alpha (GPIIb) comprises at least part of a Fg binding site on GPIIb (1). Subsequent studies demonstrated that a peptide corresponding to residues 300-312 of GPIIb alpha can bind to Fg and Vn, and is a potent inhibitor of platelet aggregation and the adhesion of activated platelets to at least four adhesive ligands: Fg, Fn, Vn, and vWf (2). Here, the production and initial characterization of polyclonal antibodies against this peptide are described. ELISAs and dot-blot assays reveal the specificity of the antibodies for the peptide immunogen. In immunoblots, the antibodies recognize GPIIb under reducing conditions. The binding of Fg to immobilized GPIIb/IIIa, the rate of clot retraction and the adhesion of stimulated platelets to Fg, fibronectin (Fn), vitronectin (Vn), and von Willebrand factor (vWf) were inhibited by these antibodies, but not by a control IgG. These results together with our earlier published data indicate that GPIIb alpha (300-312) comprises at least part of a common ligand binding site within the integrin alpha IIb subunit.
Taylor
D B
DB
Department of Biology, Illinois Benedictine College, Lisle 60532.
Derrick
J M
JM
Gartner
T K
TK
D000595:Amino Acid Sequence; D000906:Antibodies / Q000494:pharmacology*; D003018:Clot Retraction; D004797:Enzyme-Linked Immunosorbent Assay; D005340:Fibrinogen / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010974:Platelet Aggregation; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D019096:Vitronectin; D014841:von Willebrand Factor / Q000378:metabolism
D000906:Antibodies; D005353:Fibronectins; D006023:Glycoproteins; D007074:Immunoglobulin G; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; D019096:Vitronectin; D014841:von Willebrand Factor; D005340:Fibrinogen