Structural features of fibronectin synthetic peptide FN-C/H II, responsible for cell adhesion, neurite extension, and heparan sulfate binding

FN-C/H II (KNNQKSEPLIGRKKT), a heparin-binding peptide derived from the COOH-terminal heparin-binding domain of fibronectin, mediates cell adhesion for a variety of cell types and promotes neurite outgrowth. By systematic amino acid substitution of synthetic peptide analogues of FN-C/H II, the basic structural features necessary for activity have been identified in the COOH-terminal residues LIGRKK. This biologically "active" sequence has been located in several other heparin/heparan sulfate-binding proteins and may represent a potential binding motif for sulfated polyanions. NMR structural studies indicate that the COOH-terminal segment of FN-C/H II displays significant multiple-turn or helix-like character suggesting that the RKK sequence may lie on the same surface of the protein, as opposed to alternating in an extended chain motif.