Active flows drive clustering and sorting of membrane components with differential affinity to dynamic actin cytoskeleton

Several cell membrane proteins, including signalling receptors and cell adhesion receptors, bind to contractile cortical F-actin at the cytoplasmic leaflet. Interaction with contractile actomyosin and associated actin flows drives these proteins into nanoscale clusters and mesoscopic assemblies of physiological relevance. In the context of diverse actin-binding membrane proteins, we ask how a specific composition of the local cluster/assembly may be achieved. Using in vitro reconstitution together with kinetic Monte Carlo simulations our studies reveal that an interplay between differential actin-binding affinity, protein-protein interactions and actomyosin remodelling leads to specific molecular patterning within a cluster and sorting between clusters. We show that in the lamellipodia of spreading cells in vivo, actin flows also result in the sorting of high and low-affinity actin-binders. This affinity-based sorting mechanism provides an attractive means for locally controlling cell membrane composition via engagement with the active cortical meshwork beneath.