Fig. 4. α₅β₁ head in complex with Fn fragment. Projection averages are shown for (A) Fn7–10 alone, (B) α₅β₁ complex with Fn7–10 and (C) α₅β₁ complex with Fn9–10. The projection averages of the α₅β₁/Fn7–10 complexes are subgrouped (groups I, II and III) based on the orientation of the bound ligand, and several representative raw images are shown below (raw). As in Figure 2, the three most populated averages for each group are shown. The assignment of the FnIII modules (black ovals) in the complex is shown in the schematic drawing to the right. The modules missing in the averages due to linker flexibility are depicted by gray ovals. Scale bars, 100 Å.