Affinity and Valence Impact the Extent and Symmetry of Phase Separation of Multivalent Proteins

Biomolecular self-assembly spatially segregates proteins with a limited number of binding sites (valence) into condensates that coexist with a dilute phase. We develop a many-body lattice model for a three-component system of proteins with fixed valence in a solvent. We compare the predictions of the model to experimental phase diagrams that we measure in vivo, which allows us to vary specifically a binding site's affinity and valency. We find that the extent of phase separation varies exponentially with affinity and increases with valency. Valency alone determines the symmetry of the phase diagram.

Automated summary

Biomolecular self-assembly can spatially segregate proteins with a limited number of binding sites into condensates that coexist with a dilute phase. By comparing experimental phase diagrams to model predictions, we find that the extent of phase separation exponentially increases with binding site affinity and valency. Valency alone determines the symmetry of the phase diagram.