Affinity and valence impact the extent and symmetry of phase separation of multivalent proteins

TL;DR

This study models how affinity and valence influence the extent and symmetry of phase separation in multivalent proteins, providing insights into biomolecular condensate formation with experimental validation.

Contribution

Develops a many-body lattice model for multivalent proteins and compares it to in vivo experiments to understand phase separation behavior.

Findings

Phase separation extent varies exponentially with affinity.

Higher valency increases the extent of phase separation.

Valency determines the symmetry of the phase diagram.

Abstract

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 \textit{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.