Fig. 2.

Extended structures formed by proteins. (A) Protein filaments are 1D extended structures that can sustain mechanical forces. However, forces can affect the assembly of the filament and can induce filament breakage. (B) Two-dimensional extended structures are formed by proteins interacting laterally. When these 2D assemblies interact with another surface, such as the membrane, the curvature and rigidity of the assembly will determine the energies of the interaction. These interactions in turn will affect the dynamic exchange of subunits. (C) Filaments can form bundles by mechanically deforming the single filament to maximize the number of contacts between filaments. Thus, the geometry of the bonding interaction and mechanical properties of the protofilaments can regulate the bundle size.