Conformational States of Vitronectin : Preferential Expression of an Antigenic

A difference in recognition of the adhesive glycoprotein vitronectin (also called S-protein. serum spreading factor. and epibolin) by monoclonal antibody 8E6 (Hayman EG. et al. Proc NatI Acad Sci USA 80:4003. 1 983) was investigated using a competitive enzyme-immunosorbent assay and immunoaffinity chromatography. Recognition of vitronectin in serum was approximately 50-fold greater than recognition of vitronectin in plasma. Recognition of vitronectin incubated with heparin. thrombin-antithrombin Ill complex. or heparin and thrombin-antithrombin Ill complex together was 2.5-. 7-. or 32-fold greater. respectively. than recognition of vitronectin alone. Thrombin or antithrombin III by itself did not induce the antigenic change. Factor Xaantithrombin Ill was less effective than thrombin-antithrombin Ill in induction of the change. Dextran sulfate and fucoidan were more potent than heparin in induction of the antigenic change. whereas dermatan sulfate. hyaluronic acid. heparan sulfate. chondroitin sulfate. or keratan sulfate were less effective. Immunoblotting analysis of serum and of vitronectin incubated with thrombin and antithrom-