Traffic by multiple species of molecular motors

TL;DR

This paper investigates the traffic dynamics of two molecular motor species using a two-species ASEP model, analyzing densities, currents, and effects of different motor properties through simulations and analytical methods.

Contribution

It introduces a detailed analysis of two-species molecular motor traffic, highlighting the impact of unbinding and stepping probabilities on system behavior.

Findings

Mean field theory accurately predicts motor densities and currents with different unbinding probabilities.

Breaking of particle-hole symmetry occurs when motors differ in stepping probabilities.

Total motor current scales exponentially with system size, allowing extrapolation to the thermodynamic limit.

Abstract

We study the traffic of two types of molecular motors using the two-species symmetric simple exclusion process (ASEP) with periodic boundary conditions and with attachment and detachment of particles. We determine characteristic properties such as motor densities and currents by simulations and analytical calculations. For motors with different unbinding probabilities, mean field theory gives the correct bound density and total current of the motors, as shown by numerical simulations. For motors differing in their stepping probabilities, the particle-hole symmetry of the current-density relationship is broken and mean field theory fails drastically. The total motor current exhibits exponential finite-size scaling, which we use to extrapolate the total current to the thermodynamic limit. Finally, we also study the motion of a single motor in the background of many non-moving motors.