Fig. 1. MB facilitates tau phase separation.

a Structure of MB and LMTM. b Turbidity of tau solution measured at 350 nm (OD350) for different tau and MB concentrations, as indicated, in 50 mM Tris (pH 7.4) with 5% PEG8000 or 20 mM HEPES (pH 7.4) without PEG8000. c Representative fluorescence microscopy images of tau droplets with different MB concentrations. The concentrations of tau were 5 μM in 50 mM Tris (pH 7.4) with 5% PEG8000 and 20 μM in 20 mM HEPES (pH 7.4) without PEG8000. Scale bars, 10 μm. d Saturation concentration of tau (C_sat) with different MB concentrations, as indicated, in 50 mM Tris (pH 7.4) with 5% PEG8000 or in 20 mM HEPES (pH 7.4) without PEG8000. e Turbidity of tau solution (5 μM) with different concentrations of MB or DTT-reduced MB, as indicated, in 50 mM Tris (pH 7.4) with 5% PEG8000. f Turbidity of tau solution (5 μM) in the presence of a series of concentrations of MB or LMTM, as indicated, in 50 mM Tris (pH 7.4) with 5% PEG8000. g Design of the tau cysteine-less mutant. Locations of the two N-terminal inserts (N1 and N2) within the N-terminal domain (NTD), the two proline-rich regions (P1 and P2) within the proline-rich domain (PRD), the four microtubule-binding repeats (R1 to R4) within the microtubule-binding domain (MTBD), and the C-terminal domain (CTD) are indicated. h Turbidity of tau solution (5 μM) in the presence of different MB concentrations, as indicated, in 50 mM Tris (pH 7.4) with 5% PEG8000. Data in (d–f, h) are presented as mean values +/− SD of three experiments. Significance levels were determined by unpaired two-sided Student’s t test. NS non-significant. Source data are provided as a Source data file.