Fig. 2. Liquid droplet-like properties of phase-separated tau structures.

a Tau-GFP (2 µM) phase-separated structures undergo fusion events, which are characteristic of liquid droplets. Scale bars are 5 µm. b An illustrative example of tau-GFP fluorescence recovery after photobleaching (FRAP), which was used to confirm the dynamic nature of tau liquid droplets (see Fig. 5 for additional FRAP data). Scale bar is 1 µm. c Tau-GFP (2 µM) concentration within liquid droplets was estimated at an average of 210.7 μM (SD = ±71.82, Min = 33.9 μM, Max = 343.9 μM) after 2 h incubation (n = 50 droplets). Images of recombinant GFP protein at a range of 6–420 μM were used for a standard curve of GFP fluorescence signal (linear regression, r² = 0.98). Scale bar is 5 µm. The red data points and line are the GFP standard, open black circles are the individual droplets measured and the green circle indicates the mean tau-GFP droplet intensity. Data are from a representative experiment that was repeated three times with similar results. All experiments in LLPS buffer +10% PEG. Source data for b and c provided in the Source Data file.