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.