Driven transport on open filaments with interfilament switching processes

Abstract

We study a two filament driven lattice gas model with oppositely directed species of particles moving on two parallel filaments with filament switching processes and particle inflow and outflow at filament ends. The filament switching process is correlated such that particles switch filaments with finite probability only when oppositely directed particles meet on the same filament. This model mimics some of the coarse grained features observed in context of microtubule (MT) based intracellular transport, wherein cellular cargo loaded and off-loaded at filament ends are transported on multiple parallel microtubule (MT) filaments and can switch between the parallel microtubule filaments. We focus on a regime where the filaments are weakly coupled, such that filament switching rates scale inversely as the length of the filament. We find that the interplay (off)loading processes at the boundaries and the filament switching process leads to some distinctive features of the system. These features includes occurrence of variety of phases in the system with inhomogeneous density profiles including localized density shocks, density difference across the filaments and bidirectional current flows in the system. We analyze the system by developing a mean field (MF) theory and comparing the results obtained from the MF theory with the Monte Carlo (MC) simulations of the dynamics of the system. We find that the steady state density and current profiles of particles and the phase diagram obtained within the MF picture matches quite well with MC simulation results. These findings maybe useful for studying multi-filament intracellular transport.

Cargo crowding, stationary clusters and dynamical reservoirs in axonal transport

“…Apart from these, a number of modelling studies have focused on understanding traffic jams in pathological conditions, for instance, at regions of microtubule polar mismatch [13, 14], and at regions of reduced microtubule densities [15]. Lattice models with multiple lanes and exclusion processes have been used to study transport properties of cargo or motors on microtubule lanes [16–18]. A number of models for motor-driven microtubule-based transport focus on understanding general features of axonal transport as opposed to studying specific model systems [19–24].…”