The simulated systems and their curvatures are shown in Fig. . The membrane in the "Wave" system has only mean curvature, H, hence it is isomorphic to a plane. This is not true for the lipid bilayer in the "Budded" system, as it also possesses Gaussian curvature, K. An important attribute of Gaussian curvature is its insensitivity to the orientation of the constituents of the bilayer. A bowl-shaped (saddle-shaped) region always has positive (negative) Gaussian curvature, irrespective of whether the membrane bulges into the cytoplasmic or the extracellular space (and similarly for membranes other than the plasma membrane). The curvatures (bottom panels of Fig. ), while properly capture the topology of the system, exhibit some irregularities due to the use of mesh surfaces (see section 3 the Supporting Information). Even though their relative sign depends on the chosen leaflet, a strong correlation between the magnitudes of H and K is clearly apparent.