Increase in divalent cation concentration leads to dissolution of heterotypic RP3-polyU droplets and formation of homotypic polyU droplets. (a) Solution turbidity measurements of RP3-polyU droplets as a function of [MgCl2]. ([RP3] = 500 µM, 0.6x polyU wt/wt). (b) Confocal fluorescence microscopy images of RP3-polyU droplets under different divalent salt conditions. ([RP3] = 500 µM, 0.6x polyU wt/wt, 0.5 µM RP3-AF594). (c) Solution turbidity measurements of polyU coacervates as a function of [MgCl2] and [CaCl2]. (1 mg/mL polyU). (d) Confocal fluorescence microscopy image of polyU coacervates. (1.5 mg/mL polyU, 600 mM MgCl2, 0.5 µM FAM-UGAAGGAC) (1.5 mg/mL polyU, 75 mM CaCl2, 0.5 µM FAM-UGAAGGAC).