Resting platelets contain a substantial centrally located pool of glycoprotein IIb-IIIa complex which may be accessible to some but not other extracellular proteins.

摘要: Recent evidence suggests the presence in resting platelets of centrally located compartments glycoprotein (GP) IIb-IIIa. We have employed an experimental procedure which dissociates and antigenically denatures surface compartment GP IIb-IIIa allows internal to be studied immunochemically functionally intact platelets. When gel-filtered are incubated with 0.25 mM EGTA at 37 degrees C for 30 min, then supplemented min 5 calcium, they lose their ability bind complex-specific monoclonal antibody Fab fragments. However, when such subsequently stimulated thrombin, IIb-IIIa-specific Fabs again able large amounts platelet surface, concert appearance substantial receptors fibrinogen fibronectin. In immunoprecipitation experiments, we found that this thrombin-displayed pool originates from a is not labeled by lactoperoxidase-catalyzed radioiodination immunofluorescence EGTA-incubated contain sequestered upon thrombin stimulation translocated surface. Additional experiments suggest may connected it accessible some extracellular proteins, but others.