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Updated: Jan 20, 2026

Measuring Light-Switching Behavior Using an Occupancy and Light Data Logger
Published on: January 16, 2020
Divalent cations can control a switch-like behavior in heterotypic and homotypic RNA coacervates
Paulo L Onuchic1, Anthony N Milin1, Ibraheem Alshareedah2
1Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, 92037, USA.
Abstract:
Liquid-liquid phase separation (LLPS) of RNA-protein complexes plays a major role in the cellular function of membraneless organelles (MLOs). MLOs are sensitive to changes in cellular conditions, such as fluctuations in cytoplasmic ion concentrations. To investigate the effect of these changes on MLOs, we studied the influence of divalent cations on the physical and chemical properties of RNA coacervates. Using a model system comprised of an arginine-rich peptide and RNA, we predicted and observed that variations in signaling cations exert interaction-dependent effects on RNA LLPS. Changing the ionic environment has opposing effects on the propensity for heterotypic peptide-RNA and homotypic RNA LLPS, which results in a switch between coacervate types. Furthermore, divalent ion variations continuously tune the microenvironments and fluid properties of heterotypic and homotypic droplets. Our results may provide a general mechanism for modulating the biochemical environment of RNA coacervates in a cellular context.
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