Figure 4

Comparison between R21A Spc-SH3 with WT α-spectrin. The lowest-energy free (green) and bound (red) NMR structures of R21A-SH3 were superimposed on the WT X-ray structure (1SHG, blue) for backbone atoms (N, Ca, C') of residues 7–60. Only the aromatic side chains are numbered and presented in sticks. Note that all aromatics, except Trp42, are important for binding.