Figure 3.

Residues that show statistically significant $\mathrm{\Delta }{S}_{\mathit{\text{axis}}}^2$ values in the presence of Mg²⁺ (compared to the unliganded state of ϕ12 P2; top panel), Mg²⁺/GMPCPP (compared to the Mg²⁺-loaded state of ϕ12 P2; middle panel) and for the ts-mutant (the T425I mutant compared to wild-type, unliganded ϕ12 P2; bottom panel). $\mathrm{\Delta }{S}_{\mathit{\text{axis}}}^2$ between states i and j are considered to be statistically significant when $\mathrm{\Delta }{S}_{\mathit{\text{axis}}}^2=|S_{\mathit{\text{axis}}}^2(i)-S_{\mathit{\text{axis}}}^2(j)|>\sigma S_{\mathit{\text{axis}}}^2(i)+\sigma S_{\mathit{\text{axis}}}^2(j)+0.03$; $\sigma S_{\mathit{\text{axis}}}^2(i)$ is the error in the $S_{\mathit{\text{axis}}}^2$ value for the i^th state. Remote residues (defined as those that do not have any heavy atoms within 15 Å of any other atom of the binding/mutation site) are labeled. The fonts are colored based on the domain that houses a particular residue – red for fingers, green for palm, blue for thumb and yellow for C-terminal. Residues that comprise the secondary Mg²⁺-binding site (G348, E503, V507 and D470) are shown and colored green in the top panel. The catalytic residues (D349, D469 and D470) are colored cyan and the two GTP molecules are colored purple and magenta in the middle panel. The site of mutation (T425I) is colored orange (and labeled in black) in the bottom panel.