Figure 3.

Details of the triphosphate-binding site in the P-domain. MolA (A) and MolB (B)of CopA-PN wild type, those of His462Q mutant (D, E) and Ca²⁺-ATPase (C: E1·AMPPCP form (Toyoshima and Mizutani, 2004), F: E2·ATP(TG) form: PDB entry 2DQS). Side chains of important residues and AMPPCP are shown in ball-and-stick. Broken lines in light blue show likely hydrogen bonds, and those in green show coordination of the divalent cation. Broken lines in orange indicate hydrogen bonds specific to MolB (B) and Ca²⁺-ATPase (C). Small spheres represent Mg²⁺ (green), Me²⁺ (most likely Ca²⁺ in the crystal structure (Picard et al, 2007); cyan), and coordinating water molecules (red). Prepared with Molscript (Kraulis, 1991).