Figure 1

Fusion of a vesicle ($\mathrm{\text{yellow}}+\mathrm{\text{orange}}$) with a diameter of 30 nm to a planar membrane ($\mathrm{\text{green}}+\mathrm{\text{red}}$) with a linear size of 50 nm. The vesicle consists of 6869 lipids with orange heads and yellow chains (or tails). The planar membrane contains 6911 lipids with red heads and green chains. The water beads initially inside and outside the vesicle are blue and transparent, respectively. (a) Six successive snapshots, side view, from 78.5 ns up to 1334 ns after initial contact. Lipids start to undergo interbilayer flips along the contact line after 78.5 ns. This leads to a disordered bean-shaped region in which a small hemifused membrane patch nucleates at about 1177 ns. (b) The same membrane conformations viewed in a plane parallel to the planar membrane as indicated by the arrows in (a). The blue broken line corresponds to the contact line.Reuse & Permissions

Figure 2

Cumulative histograms of observed fusion times for (a) 15 nm and (b) 30 nm vesicle. Color code: violet, red, yellow, green, and gray correspond to initial molecular area $\overline{A}=1.55$, 1.55, 1.45, 1.4, and 1.35 of the planar membrane. Different shades of each color correspond to different molecular areas ${\overline{A}}_{\mathrm{ve}}$ of the vesicle membrane, see inset in the right upper corner. The clear separation of the colors reflects the strong dependence of the average fusion time on membrane tension. Histogram (b) is rather broad with a fat tail; the very long fusion times reflect the increased stability of the adhering state.Reuse & Permissions

Figure 3

Various time scales that characterize the fusion process as functions of the dimensionless molecular area $A/N{r}_o^2=\overline{A}$ for (a) 15 nm and (b) 30 nm vesicles: average fusion time $⟨t_{\mathrm{fu}}⟩$, average first flipping time $⟨t_{\alpha }⟩$, average reordering time $⟨t_{\beta }⟩$, and width $\Delta t_{\mathrm{fu}}$ of fusion time distribution.Reuse & Permissions