The goal of this project is to determine the similarities and differences among the fibronectins (FN) and fibronectin-like molecules which occur in various animal phyla. Studies of FN in higher animals have revealed the complex structure of this molecule, its variable gene structure, and its functional diversity with special attention to its interaction with the cell surface. Analysis of the protein structure from a phylogenetic view will give insight into the origins of the current gene organization, since the functional subunits of the protein reflect the organization of the gene. This project will look at two of the phyla (annelids and nematodes) to see if FN in these animals is organized into various functional subunits. Thus, a comparison of invertebrate FN structure, function and distribution will be undertaken. Fibronectin will be isolated from invertebrates by gelatin-Sepharose chromatography. Characterization of the fibronectin, its subunits, and tryptic peptides will involve molecular weight determinations amino acid analysis and isoelectric focusing. Functional properties of the protein and peptides will be assayed by observing the binding of Affi-gel beads (Bio-Rad) coupled to collagen, fibrin, and isolated plasma membranes to microtiter plates coated with FN and FN derived peptides. Immunohistochemical studies will be performed on section of invertebrates with antibodies to FN. Differences between vertebrate and invertebrate FNs will give an understanding of evolutionary changes in the molecule. Given the developmental processes of all animals and the transformation of mammalian cell lines with concomitant alterations in FN, a study of invertebrate FN may give a more unified view of the role of the extracellular matrix in development and abberations of development such as neoplasia.
