Liquid-liquid phase separation is a key organizational principle in eukaryotic cells, on par with intracellular membranes. It allows cells to concentrate specific proteins into condensates, increasing reaction rates and achieving switch-like regulation. However, it is unclear how cells trigger condensate formation or dissolution and regulate their sizes. What are the processes that allow cells to influence phase separation?
Together with colleagues from our neighboring institute MPI-BPC, we wrote a perspective article, which is now available on bioarxiv. In this article, we predict from first principles two mechanisms of active regulation by post-translational modifications such as phosphorylation: In enrichment-inhibition, the regulating modifying enzyme enriches in condensates and the modifications of proteins inhibit their interactions. In localization-induction, condensates form around an immobilized modifying enzyme, whose modifications strengthen protein interactions. We identify a range of known biomolecular condensates that follow these two mechanisms. Our model makes testable predictions that can guide studies into the many emerging roles of biomolecular condensates.