From Proteopediaproteopedia link
CRYSTAL STRUCTURE OF HEPARIN AND INTEGRIN BINDING SEGMENT OF HUMAN FIBRONECTIN
[FINC_HUMAN] Defects in FN1 are the cause of glomerulopathy with fibronectin deposits type 2 (GFND2) [MIM:601894]; also known as familial glomerular nephritis with fibronectin deposits or fibronectin glomerulopathy. GFND is a genetically heterogeneous autosomal dominant disorder characterized clinically by proteinuria, microscopic hematuria, and hypertension that leads to end-stage renal failure in the second to fifth decade of life.
[FINC_HUMAN] Fibronectins bind cell surfaces and various compounds including collagen, fibrin, heparin, DNA, and actin. Fibronectins are involved in cell adhesion, cell motility, opsonization, wound healing, and maintenance of cell shape.    Anastellin binds fibronectin and induces fibril formation. This fibronectin polymer, named superfibronectin, exhibits enhanced adhesive properties. Both anastellin and superfibronectin inhibit tumor growth, angiogenesis and metastasis. Anastellin activates p38 MAPK and inhibits lysophospholipid signaling.   
Publication Abstract from PubMed
The crystal structure of human fibronectin (FN) type III repeats 12-14 reveals the primary heparin-binding site, a clump of positively charged residues in FN13, and a putative minor site approximately 60 A away in FN14. The IDAPS motif implicated in integrin alpha4beta1 binding is at the FN13-14 junction, rendering the critical Asp184 inaccessible to integrin. Asp184 clamps the BC loop of FN14, whose sequence (PRARI) is reminiscent of the synergy sequence (PHSRN) of FN9. Mutagenesis studies prompted by this observation reveal that both arginines of the PRARI sequence are important for alpha4beta1 binding to FN12-14. The PRARI motif may represent a new class of integrin-binding sites. The spatial organization of the binding sites suggests that heparin and integrin may bind in concert.
Crystal structure of a heparin- and integrin-binding segment of human fibronectin.,Sharma A, Askari JA, Humphries MJ, Jones EY, Stuart DI EMBO J. 1999 Mar 15;18(6):1468-79. PMID:10075919
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.