Structural comparison of fibronectins from normal and transformed cells.

Comparative study of the structures of fibronectins from normal and transformed cells by partial proteolysis as well as by tryptic peptide fingerprinting and analysis of phosphorylation show that: 1) fibronectin molecules from normal and transformed cells probably have very similar primary structures; 2) the phosphorylation of fibronectin is a highly specific and conserved phenomenon; 3) fibronectin from both normal and transformed cells is phosphorylated only on serine residues; 4) although the major sites of phosphorylation in fibronectin are the same in normal and transformed cells, fibronectin from transformed cells appears to be phosphorylated to a much higher extent than that from normal cells.