Principles of cellular control of condensates

Biomolecular condensates are crucial for the spatiotemporal organization of the interior of cells. Condensates typically form since some biomolecules phase separate from the remaining cellular fluid. However, it is unclear why particular condensates form at particular locations and times. To unveil part of this mystery, I will present two principles that cells use to control condensates. First, I will focus on multicomponent phase separation. Ι will show that tuning the interactions between biomolecules allows controlling which condensates form, independent of the cellular composition. Evolution could thus have optimized proteins to form condensates robustly. Second, I will focus on driven chemical reactions that affect the condensate material. For instance, cells use post-translational modifications to modify the interactions of biomolecules. I will show that such reactions can control where and when condensates grow and how large they get. These two examples demonstrate that living cells can regulate size, number, and location of their condensates.