Fig. 4.

Confocal images of 3 FITC-labeled regulators, revealing different extents of recruitment into SH3₅–PRM₅ droplets formed by equimolar mixing of the 2 proteins at 40 µM: (A) 5 µM FITC–Ficoll 70 plus 200 g/L Ficoll 70; (B) 2.5 µM FITC–lysozyme; (C) 2.5 µM FITC–heparin; (D) 1 µM Alexa 594–SH3₅ plus 1 µM fluorescein-sodium salt, showing enrichment of SH3₅ in the droplet phase (Left, red channel; similar to Fig. 2A) and nearly equal partitions of free fluorescein label in the 2 phases (Middle, green channel). The merge of the 2 channels is shown on the Right.