抄録
Vitronectin is a cell-adhesive glycoprotein present in animal blood and extracellular matrix. To establish the molecular basis of vitronectin interactions with extracellular matrix macromolecules, the binding site of vitronectin to collagen has been investigated. Vitronectin fragments obtained by formic acid cleavage were separated by heparin-affinity chromatography followed by gel filtration chromatography. The collagen-binding activity of the fragments was assayed in terms of inhibitory activity on the binding of 125I-vitronectin to immobilized collagen. There were two groups of collagen-binding fragments. One group consisted of 5 heparin-binding fragments with estimated molecular masses of 12 kDa, 14 kDa, 16 kDa, 18 kDa, and 19 kDa in SDS polyacrylamide gel electrophoresis. The other group consisted of 2 heparin-nonbinding fragments migrating at 18 kDa and 40 kDa. These results indicate that there are two collagen-binding sites in the vitronectin molecule; one located close to the heparin-binding domain in the COOH-terminal half and the other located in the NH2-terminal half of vitronectin.
