Fibronectin structure and function, and its interactions with glycosaminoglycans.

The glycoprotein fibronectin is a multifunctional molecule that is thought to serve as an adhesive glycoprotein in binding specifically to cells as well as to a variety of extracellular materials, such as collagen and the glycosaminoglycan regions of various proteoglycans (see review by Hynes, 1976; Yamada & Olden, 1978; Mosesson & Amrani, 1980; Ruoslahti et al., 1981). Fibronectin, like collagen, can be found in animals throughout evolution in organisms as primitive as sponges (Labat-Robert et al., 1979; Spiegel et al., 1980; S . K. Akiyama, M. Johnson & K. M. Yamada, unpublished work). It exists as a cell-surface and extracellular molecule. In higher organisms it is also present in plasma in another form (see Yamada & Olden, 1978; Mosesson & Amrani, 1980; Saba & Jaffe, 1980). Major known functions attributed to fibronectin are listed in Table 1. They include biological activities as diverse as cell adhesion, non-immune host defence and regulation of certain aspects of embryonic differentiation. Related to these activities are a number of binding activities to biologically important macromolecules, e.g. proteoglycans (Table 2).