Modeling non-processive molecular motors on multiple cytoskeletal filaments*

Molecular motors stepping along cytoskeletal filaments facilitate intracellular transport and organelle positioning. Molecular motors can work either alone or cooperatively. They are often classified according to their processivity. Processive motors never unbind from the filaments during transporting whereas non-processive motors unbind from the filaments frequently. In this work, we study the collective behaviors of N processive and non-processive molecular motors stepping along one and multiple microtubule filaments in stochastic simulations using Monte Carlo methods. The motor dynamics follow biased random walks subjected to a simple exclusion process. We consider the analytical solution of velocity (V) of a collection of N processive and non-processive motors along one filament as a function of applied force (F). We compare these analytical solutions to our stochastic simulation results. We also show the simulation results of F-V relations of non-processive motors stepping along and switching between multiple filaments. In this case, the applied load is shared between the leading motors on each filament.