Differences in hyaluronate binding to plasma and cell surface fibronectins. Requirement for aggregation.

Human plasma-derived fibronectin (pFbn) and chick embryo fibroblast cell surface fibronectin (cFbn) were compared in a series of in vitro assays for binding t o glycosaminoglycans (GAG) from various sources.Substratum-attached material, adhesive material that remains attached to serum-coated tissue culture substrata following ethylene glycol bis(P-aminoethyl ether)-N,N,iV'JV"tetraacetic acid-mediated detachment of murine Balb/c 3T3 fibroblasts, was shown to be enriched, relative to whole cells, for highly N-sulfated heparan sulfatethe only GAG in these preparations that binds to Sepharose columns derivatized with either pFbn o r cFbn.Adhesive material isolated from newly attaching and spreading fibroblasts contains 50% more of this heparan sulfate than material from long term substratum-attached cells.Both forms of fibronectin bound identically to preparations of 3H-heparin either under "univalent" binding conditions, in which fibronectin or heparin were immobilized onto inert matrices of Sepharose or gelatin-Sepharose, or under the aggregating conditions of Yamada et al. (Ya-