Simulation snapshots showing structural changes in TM5 of the triple-Val mutant in POPE (Sim4). Snapshots of wild-type and mutant conformations are shown in the left-hand (A,C) and right-hand (B,D) panels, respectively. (A) Loop L5, TM2, and TM5 in the wild-type protein (B) Same features as in for the triple-Val mutant (B). (C) Effect of the triple-Val mutant on the average distances between TM5, TM2, and TM6 Cα atoms (gray spheres). Compare with the distances in Figure 6E. All distances are average values (given in Å), with standard deviations ≤ 0.6 Å. (D) Snapshot of loop L1 at the end of Sim4. Compare with Figure 6A.