title: N-terminal fibronectin 30-kDa fragment mediates the immobilization of soluble fibrin by factor XIIIa-coated polystyrene beads.
abstract: Polystyrene beads coated with thrombin-activated Factor XIII (plasma transglutaminase, plasma transamidase) retained soluble 125I-fibrin, if a 30-kDa fragment of fibronectin was present. The fragment was obtained by proteolytic cleavage of plasma fibronectin with trypsin, but was also available with plasmin or thrombin. It represented a fibrin-binding domain at the N-terminus of each of the two subunit chains and contained close to its amino end a transamidase-reactive site. Fibronectin was unable to mediate the binding of 125I-fibrin to Factor XIIIa-coated beads. 125I-fibrinogen was hardly recognized by the beads even in presence of the fibronectin fragment. The relatively slow binding of 125I-fibrin was inhibited by 0.15 mM putrescine or by a pretreatment of the coated beads with EDTA or N-ethylmaleinimide indicating the involvement of a transamidation in the binding reaction. Immobilization of 125I-fibrin in presence of the fibronectin fragment is assumed to require a covalent cross-linking of the two ligands at the immobilized transamidase giving rise to a product which is retained strongly. The possibility is discussed that a surface-attached transamidase might act as a fibrin receptor which requires the fibronectin fragment as a cofactor.
mesh_terms: D004492:Edetic Acid / Q000032:analysis; D005033:Ethylmaleimide / Q000032:analysis; D005176:Factor XIII; D005260:Female; D005337:Fibrin / Q000302:isolation & purification*; D005353:Fibronectins / Q000032:analysis*; D006801:Humans; D010446:Peptide Fragments / Q000032:analysis*; D011137:Polystyrenes; D011247:Pregnancy; D011485:Protein Binding; D011700:Putrescine / Q000032:analysis; D011503:Transglutaminases
chemical_list: D005353:Fibronectins; D010446:Peptide Fragments; D011137:Polystyrenes; D005337:Fibrin; D005176:Factor XIII; D004492:Edetic Acid; D011503:Transglutaminases; D005033:Ethylmaleimide; D011700:Putrescine