Figure 4

a) Local surface plot of the area around two escape mutant positions in domain III. Residues 307 and 311 are highly variable and have been colored green here for visibility. The faint blue area on the surface near residue 307 comes from a highly conserved aromatic residue, Phe306, which lies under the variable residue and forms a cluster with another conserved residue, Tyr326 (b).