Mechanical and kinetic factors drive sorting of F-actin cross-linkers on bundles

Significance The actin cytoskeleton plays a crucial role in cell division, motion, and internal transport. The main component is F-actin, a semiflexible polymer formed of actin monomers. For a cell to regulate and accomplish the tasks of the cytoskeleton, F-actin polymers are organized into structures by actin-binding proteins. Among these cross-linkers are proteins that join F-actin into a network with structural rigidity and can form tight, rigid bundles. Different cross-linkers perform diverse functions in cells, but how they are sorted to their functional locations is not well understood. In this work, we show how physical and chemical characteristics of the system, including nonequilibrium factors such as actin polymerization, help organize and localize cytoskeletal components.