Contrasting self-assembly pathways at the membrane

Self-assembly of protein components from solution to the plasma membrane is necessary for a variety of membrane remodelling processes. For entry into and exit from the cell, the clathrin protein and the Gag polyprotein, respectively, assemble rigid lattices that help scaffold the membrane. However, these assemblies differ in how they couple to co-factors that can separately promote either protein-protein assembly or protein-membrane recruitment. We discuss similarities between these systems that can help them to efficiently assemble only on membranes, highlighting how cooperativity plays a key role in avoiding kinetic traps. We contrast the distinct routes that these systems use for effective assembly, dependent on the valency and flexibility of their interactions, the properties of their co-factors, and the production of these proteins within cells. Using theory and models that can be simulated using reaction-diffusion software, we determine regimes where these distinct systems can maintain robust assembly, and where they can be perturbed to disrupt assembly and remodelling.