Fig. 4: Interactions between tau and MB.

a Turbidity of WT tau (5 μM) measured at different NaCl or 1,6-HD concentrations in 50 mM Tris (pH 7.4) with 5% PEG8000. The concentrations of MB were 0 and 100 μM. Data are presented as mean values +/− SD of three experiments. Significance levels were determined by unpaired two-sided Student’s t-test. NS non-significant. b Design of tau deletion mutants. c Turbidity of tau deletion variants (5 μM) measured at different MB concentrations in 50 mM Tris (pH 7.4) with 5% PEG8000. Data are presented as mean values +/− SD of three experiments. d Overlay of 2D ¹H-¹⁵N SOFAST-HMQC spectra of WT tau (18 μM) with and without 5% PEG8000 or 360 μM MB in 50 mM Tris (pH 7.4); ppm parts per million. e Differential interference contrast (DIC) micrographs of the NMR samples. Scale bars, 20 µm. f Peak amplitude ratios (I/I₀) quantified for tau with 5% PEG8000, 360 μM MB, or 360 μM azure B calculated from the ¹H-¹⁵N SOFAST-HMQC spectra. Residues omitted from the I/I₀ analysis due to lack of reliable peak assignment are designated as gray bars. g The top five docking poses of MB binding to WT tau. The N-terminus of tau is shown as a red ball. The residues which have strong interaction with MB are shown as green balls and sticks. h Tau residue-ligand binding profile calculated using the top five docking poses for MB. Source data are provided as a Source Data file.