Extended Data Fig. 3: MeCP2 forms phase-separated droplets in vitro.

a, Droplet experiments examining effect of MeCP2 concentration. MeCP2–GFP was added to droplet formation buffers with 100 mM NaCl and 10% PEG-8000. b, Droplet areas for experiments in a. Fields per condition n = 10. c, MeCP2–GFP condensed fraction for experiments in a. Fields per condition n = 10. d, Droplet experiments examining effect of salt concentration. MeCP2–GFP at 10 μM was added to droplet formation buffers with indicated NaCl concentrations and 10% PEG-8000. e, Droplet areas for experiments in d. Fields per condition n = 15. f, MeCP2–GFP condensed fraction for experiments in d. Fields per condition n = 15. g, Phase diagram of MeCP2 droplet formation. MeCP2–GFP was added to droplet formation buffers with indicated NaCl concentrations and 5% PEG-8000. Filled-in circles indicate conditions with droplets. Fields per condition n = 10. h, Droplet experiments showing MeCP2 droplet fusion. MeCP2–GFP at 10 μM was added to droplet formation buffers with 100 mM NaCl and 10% PEG-8000. i, Droplet experiments showing MeCP2 droplet FRAP. Conditions as in h. Photobleaching at t = 0 s. j, Droplet experiments examining HP1α. HP1α–mCherry at 10 μM was added to droplet formation buffers with 100 mM NaCl and 10% PEG-8000. k, DNA-Cy5 partition ratios in MeCP2–GFP droplets for experiments in Fig. 1g. Fields per condition n = 15. l, Expanded schematic of MeCP2 protein (Fig. 2a) with protein sequence conservation, net charge per residue (NCPR), and residue plots. m, Droplet experiments examining MeCP2 deletion mutants. MeCP2–GFP deletion mutants at 10 μM were added to droplet formation buffers with 100 mM NaCl and 10% PEG-8000. n, Droplet areas for experiments in m. Fields per condition n = 5. o, MeCP2–GFP condensed fraction for experiments in m. Fields per condition n = 5. Data are mean ± s.d.