The cooperative role of the transformation-sensitive glycoproteins, GP140 and fibronectin, in cell attachment and spreading.

摘要: The detergent-insoluble matrix of cultured human fibroblasts contains cytoskeletal and nuclear components, as well two major, noncollagenous glycoproteins, fibronectin GP140. These glycoproteins are stabilized by extensive intermolecular disulfide bonding. GP140, in contrast to fibronectin, is resistant digestion with trypsin not cross-reactive antisera prepared against (Carter, W. G., Hakomori, S. (1981) J. Biol. Chem. 256, 6953-6960). GP140 was partially purified, under nonreducing conditions, differential extraction trypsinized cells sodium trichloroacetate. Alternatively, a higher yield could be obtained reducing conditions urea-dithiothreitol followed molecular sieve chromatography the presence dodecyl sulfate dithiothreitol. purified contained mannose, galactose, N-acetylglucosamine residues, totaling 2.7% molecule. In addition, mild periodate oxidation reduction NaB3H4 designed label sialic acid also labeled peptide portion Amino analysis detected periodate-sensitive hydroxylysine hydroxylproline, accounting for periodate/NaB3H4-induced peptide. hydroxylated amino acids major components collagens collagen-like proteins. isolated found induce stable cell attachment spreading when coated on plastic surfaces. inhibited affinity anti-fibronectin antibodies. However, trypsinization that removed surface reduced ability bind GP140-coated surface. Metabolic labeling radioactive glucosamine during 1-h experiments incorporated into both four other carbohydrate-containing part matrix, indicating rapidly glycosylate incorporate them matrix. Long term chase indicated subject very slow turnover. Neither nor were detectable SV40-transformed either metabolic or labeling. results consistent conclusion may function cooperative manner adhesion spreading.