Figure 1.

(A) Structure of the src SH3 domain (1fmk.pdb) colored by previously reported Φ_F-values (13) on a continuous scale from red (Φ_F = 1) to blue (Φ_F = 0). Residues at which mutations increase or decrease both k_f and k_u are colored in yellow. The graphic was generated with molscript (33) and raster3d (34, 35). (B) Structure of the hydrogen bond network between the β-distal hairpin and the diverging turn (midas; refs. 36 and 37). Residues included in the double-mutant cycles are shown in red.