Fig. 3.
KvAP channel mobility in membrane nanotubes. Semilogarithmic plot of longitudinal diffusion coefficient as a function of the tube radius. Protein density in the membrane varied between 50–1,000 proteins per μm2. Cumulative data from seven measurement series providing a total of 43 data points; each point represents a mean diffusion coefficient obtained from 4 to 161 individual trajectories; the error bars correspond to SEM. Weighted fitting by Eq. 2 (blue solid line) yields membrane viscosity η = 7.3·10-10 J m-2 s and protein radius Rprot = 3.0 nm. (Inset) The same data in linear coordinates. The mobility measured on flat membrane is shown for comparison (green dashed line; Dplane = 2.2 μm2/s).