FIGURE 12.

Active site of Na⁺,K⁺-ATPase in E₂·P conformation and Ca²⁺-ATPase in the E₁ATP conformation. A, active site of Na⁺,K⁺-ATPase in E₂·MgF₄²⁻. Mg²⁺ conformation (PDB code 2XZE). B, as in A without the bound MgF₄²⁻·Mg²⁺. Arrows indicate Asp³⁶⁹ and Glu²¹⁴ and Arg⁵⁴⁴–Glu²¹⁶ and Arg⁶⁸⁵–Glu²³¹ pairs. C, active site of Ca²⁺-ATPase in E₁·AMPPCP (PDB code 1VFP) showing proximity of Arg⁵⁶⁰ and Arg⁶⁷⁸ to the bound AMPPCP. The figure was drawn with PyMOL. P domain, green; A domain, red; N domain, blue.