FIGURE 1.

Post-Albers scheme (A) and cryo-EM structural representation of pig gastric H,K-ATPase in the fluoroaluminate-bound pseudo-E₂P state (B). A, Post-Albers scheme of the proposed reaction cycle of the gastric H,K-ATPase. E₁P/E₂P conformational states giving rise to voltage jump-induced fluorescence changes of TMRM-labeled H,K-ATPase molecules are highlighted (gray box). B, structural representation based on the cryo-EM structure of the pig gastric H,K-ATPase (surface or mesh, contoured at 1 σ; EM Data Bank code 5104) and the corresponding homology model (schematic; Protein Data Bank code 3IXZ). Inset, a close-up view (from the right side of the molecule) showing the putative interaction sites of the β-subunit N terminus with the P-domain (red arrow) and αTM3 (black arrow), respectively. Color coding is indicated in the figure.