CAS Name: a2-SB glycoproteins
Additional Names: a2-opsonins; CIG; CSP; CAF; GAP A; LETS; Zeta protein
Literature References: High mol wt multifunctional glycoproteins, found on cell surfaces, in body fluids (especially plasma), in soft connective tissue matrices, and in most basement membranes. Although fibronectins apparently function as adhesive ligand-like molecules, the full range of their biological activities and relationships are still being elucidated. Their importance in cell adhesion, oncogenic transformation, reticuloendothelial system function, embryonic differentiation, phagocytosis, hemostasis, and chemotaxis is being studied. Discovered as a result of isoln of a partially purified fraction of human plasma and initially termed "cold-insoluble globulin" or CIG: P. R. Morrison et al., J. Am. Chem. Soc. 70, 3103 (1948). Subsequent studies described various proteins or factors, named according to sources or biological activities, that are now designated as fibronectins. At least two types are known to exist, termed plasma and cellular fibronectin, respectively. Both forms contain subunits of mol wt >200,000, joined by disulfide bonds. They are similar in amino acid compositions, carbohydrate structures and secondary and tertiary structures; they cannot be distinguished in biological activity in assays of cell interactions with substrates or in opsonic activity for macrophages. They differ in their effects on cell morphology, on alignment of transformed cells and on hemagglutination; they also have differences in solubility and in the number of subunits linked by disulfide bonds. Monoclonal antibody studies have indicated that the two forms are distinct: B. T. Atherton, R. O. Hynes, Cell 25, 133 (1981); K. D. Noonan et al., J. Supramol. Struct. Cell. Biochem. 5, Suppl, 302 (1981). Regulation of fibronectin biosynthesis: D. R. Senger et al., Am. J. Physiol. 245, 144 (1983). Structure-function relationships: T. Vartio, A. Vaheri, Trends Biochem. Sci. 8, 442 (1983). Role in cellular adhesion, spreading and cytoskeletal organization: I. Virtanen et al., Nature 298, 660 (1982); in phagocytosis: L. Van de Water et al., Science 220, 201 (1983); in wound healing: G. R. Martin et al., "Regulation of Tissue Structure and Repair by Collagen and Fibronectin" in The Surgical Wound, P. Dineen, C. Hildrick-Smith, Eds. (Lea & Febiger, Philadelphia, 1981) pp 110-122. Use in treatment of corneal trophic ulcer therapy: T. Nishida et al., Arch. Ophthalmol. 101, 1046 (1983). Review of role in cellular adhesion: S. K. Akiyama et al., J. Supramol. Struct. Cell. Biochem. 16, 345-358 (1981); role in inflammation: D. F. Mosher et al., Adv. Inflammation Res. 2, 187-207 (1981); C. Bianco, Ann. N.Y. Acad. Sci. 408, 602-609 (1983); actvity in various disease states: S. K. Akiyama, K. M. Yamada, "Fibronectin in Disease" in Monographs in Pathology No. 24, N. Kaufman, Ed., entitled "Connective Tissue Diseases", B. M. Wagner et al., Eds. (Williams & Wilkins, Baltimore, 1983). General Reviews: E. Pearlstein et al., Mol. Cell. Biochem. 29, 103-128 (1980); M. W. Mosesson, D. L. Amrani, Blood 56, 145-158 (1980); E. Ruoslahti, J. Oral Pathol. 10, 3-13 (1981); R. O. Hynes, K. M. Yamada, J. Cell Biol. 95, 369-377 (1982); R. O. Hynes, Sci. Am. 254, 42-51 (1986).