Driven Transport on open filaments with inter-filament switching processes

TL;DR

This paper models bidirectional particle transport on two parallel filaments with correlated filament switching, revealing complex phase behavior and density profiles, and compares mean field theory with simulations for insights into microtubule-based intracellular transport.

Contribution

It introduces a correlated filament switching mechanism in a two-filament driven lattice gas model, capturing features of microtubule transport and analyzing phase behavior.

Findings

Multiple inhomogeneous density phases observed

Mean field theory agrees well with simulations

Filament switching influences density and current profiles

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 {\it 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.