Figure 2.

Fluorescence micrographs of a TR-doped syb-2-containing vesicle docked to (A) a ΔN49-complex-doped s-PSM and (B) a ΔN49-complex-doped f-PSM together with the corresponding trajectories derived by single-particle tracking (white line) over a time period of several seconds. Scale bars, 1 μm. (C) Probability density of the position of the docked vesicle in the f-PSM. (D) MSD versus time-interval plot derived from the trajectory of the f-PSM docked vesicle shown in (B) over a larger time period of 15 s, showing confined diffusion inside the f-PSM. (E) MSD-versus-time-interval plots of the first 20 time steps of three exemplary vesicles docked to f-PSMs, showing that the vesicles freely diffuse on a short timescale. Diffusion coefficients, D, of 0.55 (red), 0.36 (blue), and 0.27 μm²/s (green) were obtained from the slope (4D). The corresponding trajectories are depicted in the inset of (E) for a time lapse of 1 s. The grid lines are 200 nm long. (F) Distribution of the diffusion coefficients obtained for 38 vesicles docked to f-PSMs. A Gaussian distribution was fit to the histogram with a maximum of 0.42 μm²/s (σ = 0.15 μm²/s). To see this figure in color, go online.