Fig. 2. Condensates arise through a network of heterotypic and homotypic interactions.

Condensates form through phase separation of multiple types of macromolecules. In RNP granules, for example, multivalent proteins and RNA molecules participate in a network of homotypic and heterotypic interactions that collectively determine the concentration threshold for LLPS and the material properties of the resulting condensate. The material properties of biomolecular condensates, such as viscosity, elasticity, and surface tension of the dense phase are governed by the extent of physical crosslinking and the timescales for making and breaking crosslinks within condensates. These material properties influence the spatial organization and diffusion of macromolecules within the dense phase, as well as selective permeability to molecules entering the condensate. These material properties are tightly regulated and directly linked to condensate function.