The cell attachment domain of fibronectin. Determination of the primary structure

The complete amino acid sequence of the cell attachment domain of human plasma fibronectin (Pierschbacher, M. D., Hayman, E. G., and Ruoslahti, E. (1981) Cell 26, 259-267) has been determined by automated sequential degradation of a peptic fragment comprising this region and of peptides derived from this fragment by digestion with thermolysin, staphylococcal V8 protease, cyanogen bromide cleavage, and partial acid hydrolysis. The fragment contains 108 residues with isoleucine and methionine as the NH2- and carboxyl-terminal amino acids, respectively. No cysteines are present. The calculated molecular weight of the cell attachment fragment, based on the amino acid sequence, is 11,482, which is in good agreement with the molecular weight estimated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and ultracentrifugation. There are no homologies in this fragment with other published sequences. The implications of the structure of the cell attachment fragment to the molecular mechanism of cell-fibronectin interaction are discussed.