Fig. 5. Coordination of the Mg²⁺ ion in wild-type Kar3. The bound Mg²⁺ of wild-type Kar3 has a tetragonal bipyramidal or octahedral coordination due to the P_β oxygen, the hydroxyl group of T481 and four water molecules that also interact with D626 of switch II (cyan), R585 and T587 of loop L9, and N593 of helix α3a. R585 is hydrogen bonded by a water molecule to the D626 side chain that interacts with the Mg²⁺.