Surface activation of the cell adhesion fragment of fibronectin.

We have isolated a 105 kD chymotryptic cleavage fragment of fibronectin (termed F105) and have studied its interaction with cell surfaces. On a molar basis, F105 is as effective as intact fibronectin in promoting the adhesion of fibroblastic CHO cells to tissue culture dishes; however, F105 lacks the heparin- and gelatin-binding domains of the intact molecule. When F105 is absorbed onto chemically modified latex beads bearing positive or negative charged groups, the F105 beads bind to CHO cell surfaces in a specific fashion. Unmodified latex beads coated with F105 do not bind to CHO cells, even though the same amount of F105 is absorbed to the bead as in the case of charged beads. These results suggest that F105 must undergo a bead surface-induced activation in order to acquire the ability to interact with cells.