Relative coordination of Mg²⁺ and ATP in the asymmetric ATP-bound state of P-gp.

<p>Side view of NBD1 (gold) and the superimposed NBD2 (silver) the central conformation from A) Run C and B) the branched D series simulations as determined by cluster analysis. The bound ATP and Mg²⁺ is shown for both NBDs. The Walker A (blue), Walker B (purple) and Signature motifs (cyan) are shown as ribbons. The ATP bound to NBD1 and NBD2 are red and orange licorice representations, respectively. The ATP β-phosphate is in spacefill. Mg²⁺ bound to NBD1 and NBD2 are dark and light green, respectively. The Walker B Asp and Glu are shown in licorice representation. Motifs from NBD1 are bold and motifs from NBD2 are pastel. The distance between the center of mass of Mg²⁺ and the ATP β-phosphate pair is shown as a dashed line. C) & D) Plot of the Mg²⁺ and β-phosphate distance over time for the original Runs C and D1 to D4 and the three branched D series simulations for C) NBD1 and D) NBD2.