Figure 4.

Methods for setting up and maintaining curvature. (A) Scaffolding approach, employing a ‘wall’ of virtual beads (orange) that sustain membrane curvature by repulsive forces between the beads and lipid tails. Pure POPC membrane, set-up using TS2CGv1.1 [43]. The semi-transparent membrane is the periodic extension of the simulated box. (B) Scaffolding approach, where the membrane is attracted to a solid support with a hole. A cross-section through the hole is shown. Membrane of DOPC (blue) and POPI_P2 (red). Set-up using the protocol in Ref. [50]. (C) Lipid asymmetry-induced curvature. The anisotropy is maintained by virtual repulsive forces between POPC (blue) and POPS (red). Membrane fluctuations are suppressed by harmonic position restraints. Set up following Ref. [54]. (D) Virtual forces can generate and maintain a membrane curvature defined by a set of collective variables. Here, the virtual forces are harmonic restraints on the distance between a virtual bead (orange) and a section (yellow) of a POPC membrane. Set-up using EnCurv [48]. (E) The membrane is compressed in one direction (buckling) and then the box dimensions are fixed. Membrane fluctuations are avoided by position restraints. Mixed membrane of POPC (blue), POPS (red) and cholesterol (brown). Set up using Refs. [55,56]. (All original figures, generated for this review).