Summary
The binding of fn to collagen (type I) fibres has been found to resemble that of vWf
in the following respects: 1. Binding is rapid, specific, saturable, similar at 4
and 37°C, and reduced by increasing ionic strength.
2. Binding is not inhibited by native, monomeric collagen, suggesting a multivalent
mechanism of interaction.
3. Binding of fn occurs to a variety of collagen fragments (after their renaturation
and polymerization), including, for example, the collagenase-derived TCA and TCB 3A
and lA molecular fragments and the peptides al(I)CB3, 6b, 7 and 8 obtained by cleavage
with cyanogen bromide (CB), suggesting a wide distribution of binding sites on the
native collagen molecule.
4. As judged by the effect of heat-treatment, the native conformation of fn is required.
5. Chemical modification indicates the involvement of arginyl residues in collagen
and carboxyl groups in fn. However, fn and vWf did not compete with one another in
binding to collagen, suggesting the participation of different collagen
arginyl residues in the two interactions.
Fn-binding differed from that of vWf in that the former was inhibited by denatured
rnonomeric collagen (gelatin). Fn-binding was also inhibited by the fragment TCA in denatured form. The inhibitory activity was lost after chemical modification of
arginyl residues in gelatin. Our results suggest that fn binding to collagen fibres
and gelatin involves the same widely-distributed spectrum of binding sites.
Keywords
Collagen - Fibronectin - von Willebrand factor
