Effect of Biotinylation on Fibrinogen Function and Fibrinogen-Platelet Interaction

Abstract Biotinylation of antibodies to be used in immunolocalization studies is a well established approach to mapping epitopes in biological specimens at both the light and ultrastructural level. Biotinylation of antibodies does not appear to significantly alter their interaction with antigen. A similar approach has been proposed for examining ligand interaction with receptors. Producing a soluble biotinylated ligand that behaves similarly to unlabeled ligand avoids the problems introduced by particulate labels such as ferritin, gold and latex. Particulate labels for ligands can be especially problematic in studies of receptor behavior in live cells since viable cells may directly react to the particulate probe itself. The interaction of plasma fibrinogen with its receptor on blood platelets, GPIIb-IIIa, is required for platelet-platelet cohesion and subsequent formation of a hemostatic platelet plug at sites of vascular injury. To study the events that follow binding of fibrinogen to its receptor5 we have produced a series of fibrinogens biotinylated with molar ratios of biotin:fibrinogen that range from 5 to 50.