J. Biol. Chem., Vol. 255, Issue 21, 10017-10020, Nov, 1980
Isolation and characterization of a heparin-binding domain of cellular fibronectin
M Hayashi, DH Schlesinger, DW Kennedy and KM Yamada
A protease-resistant functional polypeptide domain of fibronectin that
contains a heparin-binding site has been purified from chick cellular
fibronectin following pronase digestion, heparin-Sepharose affinity
chromatography, and molecular sieve chromatography on Sephacryl S-200. This
polypeptide migrates as a single band of apparent Mr = 50,000 in sodium
dodecyl sulfate-polyacrylamide gel electrophoresis with or without
reduction by dithiothreitol. It has a Stokes radius of 35 to 37 A and a
calculated frictional ratio of 1.4 to 1.5. Its amino acid composition is
unusual in that cysteine and methionine constitute only 1 and 2 mol/mol of
the polypeptide, respectively. The NH2-terminal amino acid sequence is
Glu-Asp-Asp. In contrast to intact fibronectin, the heparin-binding
polypeptide contains virtually no neutral sugars. This 50,000-dalton domain
is inactive in four bioassays for intact fibronectin, including
hemagglutination, spreading of cells on tissue culture plastic, restoration
of alignment of tumor cells, and attachment of cells to collagen. Moreover,
excess amounts of this polypeptide do not inhibit the activity of intact
fibronectin in all of these assays; these results suggest that the
heparin-binding domain does not contain a cell surface-binding site. This
domain of fibronectin appears to be a unique region free of carbohydrate
that is a globular, protease-resistant functional site.
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