Fig. 1. Formation of IDR protein liquid droplets. (a) Spherical liquid droplet formation by STA-induced clustering of biotinylated FUS IDRs and biotinylated SUMO-fused FUS IDRs. Scale bars: 10 μm. (b) FRAP measurement of dynamic protein diffusion inside FUS droplets at 5 min after phase separation. FRAP recovery curves (left) and images (right) are shown. Error bars: 1 s.d. (n = 15 from three independent experiments). Scale bars: 5 μm. (c) Fluorescence images of dynamic fusion between IDR droplets for three IDR scaffolds. Scale bars: 5 μm.