Fig. 3: PP reduces the surface tension of SON IDR2 condensate.

a, b CETSA of SON (a) and GFP::SRSF2 (b) with 3 µM PP. Both representative blot and quantification are shown (SON: n = 6 and 5 quantifications collected from six and five separate CETSAs for DMSO and PP, respectively; GFP::SRSF2: n = 3 quantifications collected from three separate CETSAs for DMSO and PP). c Computational prediction of IDR in mouse SON. d Diagram illustrating how surface tension influences droplets coalescence kinetics. e, f Representative images of droplet formation assay with different recombinant proteins (e) and quantification (f) of area-normalized perimeter changes in the time span of 20 min with 125 mM NaCl (n = 3 quantifications from three separate droplet formation assays for each treatment). g Diagram of the optical tweezer set up. Image created, in part, with BioRender.com. (h) Force recording as well as time lapse bright field images of condensate stretching without PP. i Force recording as well as time lapse fluorescent and bright field images of condensate stretching with 500 nM PP. j, k Quantification of the number of ruptured/unruptured events (j) and the maximum and rupture force (k) of ruptured SON IDR2 condensates with increasing concentration of PP (n = 3, 4, 6, 8 independent measurements for 10, 25, 100 and 500 nM of PP, respectively). All data mean ± S.E.M. Statistical tests used: mixed-effects analysis for (a, b). Ordinary one-way ANOVA for (f). Chi-square test for trend for (j). Kruskal-Wallis test for (k). Western blot raw blot images for (a, b) are provided in the source data file.