Fig. 1. Domain structure of fibronectin (FN). FN consists of type I (rectangles), type II (ovals) and type III (circles) repeats. Sets of repeats constitute binding domains for fibrin, FN, collagen, cells and heparin, as indicated. The three alternatively spliced segments, EIIIA, EIIIB and V (or IIICS), are in yellow. The assembly domain and FN-binding sites are highlighted in orange. SS indicates the C-terminal cysteines that form the dimer.