Riccardo Rossetto, Max Planck Institute for Dynamics and Self-Organization

Phase separation in a compartment with matter exchange and dimerization

In biological cells, patterns form in compartments of various dimensionalities. For instance, proteins form structures in biological membranes, which can be conceptualized as a two-dimensional compartment that exchanges material with the bulk cytosol. Moreover, the involved proteins often also form short polymers and interact unspecifically with each other. We describe this situation with a thermodynamically consistent minimal model, which accounts for phase separation, dimerization, and material exchange between bulk and a generic compartment. While these mechanisms are understood individually, interesting nonlinear effects emerge from their combination. We illustrate this by explaining experimental data of the PAR patterning system, where dimerization boosts membrane binding, presumably to control PAR patterns. More broadly, our general model unveils fundamental mechanisms of controlling phase separation occurring in a compartment and will help us explain more biological observations in the future.