Figure 4. Preferential adsorption of VM-GFP onto smaller vesicles is concentration dependent.
(A) Membrane fluorescence intensity as a function of vesicle diameter for increasing bulk concentrations of VM-GFP. At higher concentrations, vesicles with a diameter below a critical value (Dc) of ∼ 4 μm were preferentially labeled. (B) Membrane fluorescence intensity as a function of VM-GFP concentration for different vesicle diameters (indicated diameters are +/- 0.5 μm). Above Dc, all data points were similar and well approximated by a linear fit (dotted line), whereas below Dc, the isotherms were steeper and deviated from linear. (C) Typical behaviors for small (1.5 +/- 0.5 μm) and large (6.5 +/- 0.5 μm) vesicles, and theoretical curves obtained using a model for cooperativity (11). Data points are mean +/- SD measured on N vesicles (N=3-26), resulting from 3 independent experiments.