Fig. 7.
MT-associated protein Tau-induced irreversible MT bundling. Reversibility experiments confirm that the short-range attractions are because of Tau. (A) With no Tau, SAXS data analysis shows that an osmotic pressure-induced (1.63 wt% 20k PEO) RBMT phase (upper profile; aR = 17.3 nm and bR = 30.9 nm) relaxes into an NMT by diluting PEO to 0.09wt% (lower profile). (B) In the presence of Tau (Φ3RS = 1/10), a similar dilution from 1.63 to 0.09 wt% 20k PEO shows that the bundled state remains (showing the presence of Tau-induced short-range attractions), but the bundled phase now transitions from the buckled RBMT phase (upper profile; aR = 17.5 nm and bR = 32.7 nm) to the unbuckled HMT phase (lower profile; aH = 32.2 nm) because of the large dilution of PEO as described in the text. SAXS data were analyzed, and they presented fit parameters extracted with fitted model scattering curves (red lines) corresponding to the model appropriate structure and form factor as described in text.