Molecular-simulation system comprising two ATP synthase dimers in a model lipid bilayer. (A and B) Views of the system along the perpendicular to the membrane and along the membrane plane, respectively. The calculation is based on a CG representation of all molecular components (Materials and methods). The ATP synthase dimers are shown in yellow in a surface representation. Lipid molecules are represented with spheres, with the head groups (choline and phosphate) in purple and the acyl chains in gray. The solvent is omitted for clarity. The number of particles in the system is ∼6 million. (C) Magnified view of an ATP synthase dimer seen along the membrane plane. The structure is based on earlier cryo-EM studies. In the dimer, the monomers are approximately at a right angle.