Complete primary structure of the collagen-binding domain of bovine fibronectin

The complete amino acid sequence of the collagen-binding domain of bovine plasma fibronectin has been determined. The fragment, generated by digestion of fibronectin with plasmin and chymotrypsin, contains 340 residues (260-599 of fibronectin) with threonine and tryptophan as the amino-terminal and carboxyl-terminal amino acids, respectively. 24 half-cystines and no cysteines are present in the sequence. Three glucosamine-based oligosaccharide groups are attached to Asn-399, Asn-497 and to Asn-511, respectively. Two of the three types (I and II) [Petersen et al. (1983) Proc. Natl Acad. Sci. USA 80, 137-141] of internal homology occur in the fragment, namely four of the at least twelve stretches of type I sequence homology, 'fingers', and two stretches of type II homology. The type I homology is present in two other plasmic fragments from fibronectin, while the type II homology has been found in the collagen-binding domain only.