Fig. 4: Specific recruitment of BRG1 into SS18 phase-separated condensates through tyrosine residue-mediated multimerization.
a Co-IP experiments testing the self-association ability of SS18 or its mutants. Extracts were prepared from HEK293T cells transfected with combinations of plasmids, as indicated. The bottom panel shows 3% of the Myc-SS18 as input for each IP. Representative SDS-PAGE analysis (b) and quantitative data (c) for sedimentation assay of SS18 WT, mutants, or various SS18/BRG1(1-282) mixtures, as indicated. The concentration of each protein is 60 µM. The band intensities of proteins were quantified with Image J v1.8.0 software. The statistical data represent results from three independent batches of sedimentation experiments and are plotted as mean ± SEM. d Fluorescence and bright-field images of SS18 WT or mutant droplets at the protein concentration of 60 µM. Liquid droplets are enriched in Alexa Fluor 488-labeled SS18 WT or mutant. The scale bar indicates 10 μm. e Representative fluorescence images of GFP-SS18(WT), GFP-SS18(Y21S), and GFP-SS18(3M) in HEK293T cells. The scale bar indicates 5 μm. f Co-localization of GFP-SS18-WT or mutants and Cherry-BRG1 in HEK293T cells. The scale bar indicates 5 μm. g Representative fluorescence and bright-field images of the mixture of Alexa Fluor 488-labeled SS18 or mutants (60 µM) and Cy3-labeled BRG1(1-282) (60 µM) in the buffer comprised 50 mM Tris-HCl pH 7.5 and 150 mM NaCl at room temperature. The scale bar indicates 10 μm.
