FIGURE 4.
Coordination of the Mg2+ ion. The Mg2+ ion is tightly coordinated by oxygen atoms of the β- and γ-phosphate, Ser233 of switch I, Thr112 of the P-loop, and two water molecules. The ion location is quite similar to that seen in the Eg5·ADP structure (18), in which the Mg2+ ion is coordinated by Thr112, a β-phosphate oxygen atom, and four water molecules.