Figure 42.

Different mechanisms of lipid flip–flop. (top) Push-in flip–flop. (middle) Sliding flip–flop. (bottom) Rotation flip–flop. Water particles are shown as blue spheres and lipid molecules performing a flip–flop are colored, whereas other lipid molecules are gray. Adapted with permission from Arai et al.⁹⁵⁶ Copyright 2014 AIP Publishing.