CROWDING-INDUCED ORGANIZATION OF CYTOSKELETAL ELEMENTS .2. DISSOLUTION OF SPONTANEOUSLY FORMED FILAMENT BUNDLES BY CAPPING PROTEINS

Through calculations of molecular packing constraints in crowded solut ions, we have previously shown that dispersions of filament forming pr oteins and soluble proteins can be unstable at physiological concentra tions, such that tight bundles of filaments are formed spontaneously, in the absence of any accessory binding proteins. Here we consider the modulation of this phenomenon by capping proteins. The theory predict s that, by shortening the average filament length, capping alleviates the packing problem. As a result, the dispersed isotropic solution is stable over an expanded range of compositions.