Exchange Dynamics of Biomolecular Condensates

Biomolecular condensates are dense assemblies of biological molecules that segregate out of the intracellular milieu via liquid-liquid phase separation. One of their key features is that they constantly exchange components with the cellular environment. It has previously been shown that this material exchange can influence condensate function via the rate of biochemical reactions occurring in condensates and the speed with which a condensate responds to environmental changes. Motivated by recent experimental evidence that condensates of a single type of biomolecule can consist of multiple species with drastically different mobilities, we theoretically derive diffusion-reaction equations to model a two-species system, where the two species represent molecules of different mobilities within the condensate. Using finite difference methods, we study the diffusion processes and characteristic timescales that mediate the dynamical exchange of the dilute and dense phases of such a two-species system.