Fig. 1.
Schematic drawing of rat FN and the recombinant fragments made in this study. Shaded boxes mark the three alternatively spliced regions in FN. Each of the recombinant fragments used is illustrated, and the approximate molecular size shown. The α5β1 recognition sequence, Arg-Gly-Asp (RGD) is located in the 10th type III repeat. The α4β1 binding sequence Leu-Asp-Val (LDV) is located in the V25 fragment. Note the pattern of V region splicing, as described in the introductory remarks, shown in the two sets of recombinant FNs: 8V120 and 11V120, V95, and V0. The V120 form contains a 25 amino acid sequence (V25) that includes the LDV sequence to which α4β1 binds. This is shown as a light gray box. In those recombinant FNs in which this sequence was mutated to LAV (to abolish α4β1 binding), the V25 region is shown as a black box. Construction of the recombinant fragments is described in Materials and Methods. All fragments carry at their C termini the 232 amino acid sequence of the human IgG1 Fc that is represented by the filled rectangles.