Figure 1.

MK2 structure and location of mutagenesis sites. MK2 is represented as a ribbon diagram, a composite of Protein Data Bank entries 1KWP and 1NXK. The mutagenesis sites (see Table 1 and Additional File 1 Table S7) are colored by tactic: (1) N-terminal variations, purple/blue/cyan, C-terminal variations, yellow/orange/red; (2) entropy-reducing surface mutations, light-green; (3) internal deletions, grey-green; and (4) pseudoactivation mutations, dark-green. Missing residues are represented as dots.