Binding of gelatinases A and B to type-I collagen and other matrix components.

Matrix sequestration of matrix metalloproteinases may be important for the facilitation of remodelling events and the migration of cells through the extracellular matrix. Using an ELISA technique we studied the ability of pro and active forms of gelatinases A and B (GLA and GLB) to bind to matrix components and the contribution made by the different enzyme domains. Pro and active forms of GLA and GLB bound to type-I and type-IV collagens, gelatin and laminin films. Binding to collagens occurred exclusively via the N-terminal portion of the molecule in both of the gelatinases; deletion of the fibronectin-like domain in GLA abolished binding. Fibronectin was shown to compete with GLA, confirming that binding occurs through this domain. GLA and GLB competed for binding to collagen type I, whereas collagenase and stromelysin bound to different sites and could be co-localized with the gelatinases. We conclude that gelatinases have different binding specificities from those previously documented for stromelysin and collagenase, which bind through their C-terminal domains to collagen fibrils.