Fig. 6.

Waiting times for membrane energy fluctuations to attain a threshold value increase with the energy value and decrease with number of SNAREs. (A) Membrane energy versus time in a simulation with 16 SNAREpins. Three hypothetical fusion energy thresholds are indicated. Energy fluctuations reach 14 $k_{B}T$ once every ~2 $\mu s$, 16 $k_{B}T$ once every ~7 $\mu s$, and 18 $k_{B}T$ once every ~20 $\mu s$, The mean energy is indicated (black line). (B) Fusion time versus hypothetical value of the fusion energy threshold, $E_{\text{fusion}}$, for four values of the number of SNAREs, $N_{\text{SNARE}}$. The fusion time is the mean waiting time for the first instant that an energy fluctuation reaches $E_{\text{fusion}}$. Fusion time increases with $E_{\text{fusion}}$ and $N_{\text{SNARE}}$. Error bars are 95% confidence intervals.