FIGURE 1.

Schematic illustrations of: (A) the lateral pressure profile, p(z), of a lipid bilayer, revealing regions of expansive (positive) pressures and regions of large tensile (negative) pressures; (B) lamellar and non-lamellar lipid aggregates formed by self-assembly processes in water. The different structures have different senses of curvature and are arranged in accordance with the value of the phenomenological molecular packing parameter P; (C) Lipid monolayers with positive, zero, and negative (from top to bottom) curvature determined by the shape of the lipid molecules. Stable lipid bilayer (center) formed by two opposing lipid monolayers. If the monolayers were not constrained by being in the bilayer, they may curve as shown at the top and the bottom illustrations. In the latest cases, the stable bilayer would suffer from a built-in curvature stress. Adapted from Mouritsen (2011a) with permission.