BAR scaffolds drive membrane fission by crowding disordered domains

Wilton T. Snead; Wade F. Zeno; Grace Kago; Ryan W. Perkins; J Blair Richter; Chi Zhao; Eileen M. Lafer; Jeanne C. Stachowiak

Membrane coverage by proteins was estimated for each vesicle by dividing the area occupied by membrane-bound proteins by the corresponding vesicle surface area. The projected membrane footprint of N-BAR, Amph-FL, and Amph CTD ∆SH3 monomers were assumed to be: 16.5 (Adam et al, Scientific Reports 2015) (Adam et al., 2015) , 79, and 79 nm 2 , respectively. The average membrane coverage within an experiment was estimated as the mean of all individual vesicle coverage values. Experiments were repeated three times for each protein concentration. Fig. S2D ,E and Fig. 3D plots the mean ± first s.d. of the coverage values from the three experiments. To confirm the validity of this analysis approach, we also plotted the area of membrane-bound proteins as a function of vesicle surface area, as shown in Fig. S2M for the 1 µM Amph CTD ∆SH3 dataset. The slope of a linear fit to these data provides an alternative estimate of membrane coverage. The slope of 0.21, or 21% coverage, agrees well with 24% membrane coverage in Fig. 3D that was estimated using the method described above.