FIBRONECTIN HARBORS ANTICELL ADHESIVE ACTIVITY

Effect of a fibronectin (FN) fragment derived from the carboxyl-termin al heparin-binding (Hep 2) domain on cell adhesion was studied. A 30-k Da Hep 2 fragment showed no significant effect on adhesion of Mardin D arbyn caine kidney (MDCK) cells to FN substrate, whereas after exposur e to urea, the Hep 2 fragment suppressed the MDCK cell adhesion to FN in an incompetitive fashion. This anti-cell adhesive Hep 2 fragment pr eferentially inhibited the RGD (Arg-Gly-Asp)-dependent cell adhesion t o FN. No significant binding of the Hep 2 fragment with FN was detecte d. Additionally, data of flow cytometry showed the presence of specifi c binding site for the Hep 2 fragment on MDCK cell surface. These resu lts indicate that the Hep 2 domain of FN has a cryptic molecular regio n having the anti-cell adhesive activity that is probably transduced b y a putative cell surface receptor. (C) 1996 Academic Press, Inc.