FIGURE 2.

The diffusive behavior of Tau molecules is independent of the total Tau concentration. A, diffusion coefficients of individual hTau40-TMR molecules at different Tau concentrations. Concentration of tubulin was 50 nm. B, distribution of diffusion coefficients of 170 hTau40-TMR molecules at various total Tau concentrations. A Gaussian fit (black curve) yielded a mean value for the diffusion coefficient D of 0.153 ± 0.019 μm²/s. C, interaction times between individual hTau40-TMR molecules and Cy5-labeled MTs at different Tau concentrations in the presence of 50 nm tubulin. D, distribution of interaction durations of 170 hTau40-TMR molecules at various total Tau concentrations. An exponential decay (black curve) fitted to the data yielded, when corrected for photobleaching (supplemental Fig. S5D), a diffusion time constant of 24.41 ± 1.78 s. E, distances on MTs scanned by individual hTau40-TMR molecules during their interaction times at different Tau concentrations in the presence of 50 nm tubulin. F, distribution of observed distances on MTs scanned by individual hTau40-TMR molecules (n = 170) at various total Tau concentrations.