Current practices in the study of biomolecular condensates: a community comment

The realization that the cell is abundantly compartmentalized into biomolecular condensates has opened new opportunities for understanding the physics and chemistry underlying many cellular processes1, fundamentally changing the study of biology2. The term biomolecular condensate refers to non-stoichiometric assemblies that are composed of multiple types of macromolecules in cells, occur through phase transitions, and can be investigated by using concepts from soft matter physics3. As such, they are intimately related to aqueous two-phase systems4 and water-in-water emulsions5. Condensates possess tunable emergent properties such as interfaces, interfacial tension, viscoelasticity, network structure, dielectric permittivity, and sometimes interphase pH gradients and electric potentials6, 7, 8, 9, 10, 11, 12, 13–14. They can form spontaneously in response to specific cellular conditions or to active processes, and cells appear to have mechanisms to control their size and location15, 16–17. Importantly, in contrast to membrane-enclosed organelles such as mitochondria or peroxisomes, condensates do not require the presence of a surrounding membrane.