Fig. 1.
The finite subunit pool model. (a) A cartoon of filament assembly and disassembly for a single filament in a fixed volume (green box) containing a pool of Ntot subunits. We assume that filaments are assembled only at the nucleator. (b) Rate of assembly and disassembly as a function of the filament length for a single filament being assembled from a pool of subunits whose total number is Ntot; n* is the filament length in steady state when assembly and disassembly match up. (c) One multifilament structure (bounded by the dashed red line). All of the nucleators in the structure are identical and have assembly dynamics described in part a. (d) Two multifilament structures in a common pool of subunits. Each structure is assembled by only one type of nucleators; the purple nucleators are characterized by different rate of assembly and disassembly than the orange ones.