Modulation of an RGDS binding site on the platelet membrane glycoprotein IIb-IIIa complex.
Fibronectin, von Willebrand factor, and fibrinogen each bind to the glycoprotein IIb-IIIa complex on activated platelets via an arg-gly-asp-ser (RGDS) sequence present within the adhesive proteins. Both the IIb and IIIa polypeptides of the IIb-IIIa complex on thrombin activated platelets are specifically and extensively labeled by a radiolabeled, photoactivatable arylazide derivative of the RGDS sequence when the labeling is performed in the presence of concentrations of Ca++ or Mg++ approaching 0.5 mM. In contrast, labeling of unactivated platelets, ADP activated platelets, or thrombin activated platelets in the presence of low concentrations of divalent cations resulted in restriction of labeling to the IIb polypeptide of the complex.
Santoro
S A
SA
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
Lawing
W J
WJ
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000345:Affinity Labels; D001665:Binding Sites; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen; D008274:Magnesium / Q000494:pharmacology; D009842:Oligopeptides / Q000378:metabolism*; D010777:Photochemistry; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology
D000345:Affinity Labels; D002413:Cations, Divalent; D009842:Oligopeptides; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D000244:Adenosine Diphosphate; D005340:Fibrinogen; C046617:arginyl-glycyl-aspartyl-serine; D013917:Thrombin; D008274:Magnesium; D002118:Calcium