Properties of tug-of-war model for cargo transport by molecular motors

TL;DR

This paper provides a comprehensive analysis of the tug-of-war model for cargo transport by molecular motors, identifying all stable states and how initial conditions and parameters influence cargo velocity and direction.

Contribution

It offers a complete characterization of the stable steady states in the tug-of-war model, enhancing understanding of bidirectional cargo transport mechanisms.

Findings

Identification of all stable steady states including uni-, bi-, and tristability.

Cargo velocity and direction depend on initial motor binding and parameters.

Predictive framework for cargo movement based on stable states and initial conditions.

Abstract

Molecular motors are essential components for the biophysical functions of the cell. Our current quantitative understanding of how multiple motors move along a single track is not complete; even though models and theories for single motor chemomechanics abound. Recently, M.J.I. M$\ddot{\rm u}$ller {\em et al.} have developed a tug-of-war model to describe the bidirectional movement of the cargo (PNAS(2008) 105(12) P4609-4614). Through Monte Carlo simulations, they discovered that the tug-of-war model exhibits several qualitative different motility regimes, which depend on the precise value of single motor parameters, and they suggested the sensitivity can be used by a cell to regulate its cargo traffic. In the present paper, we carry out a thorough analysis of the tug-of-war model. All the stable, i.e., biophysically observable, steady states are obtained. Depending on several parameters, the system exhibits either uni-, bi- or tristability. Based on the separating boundary of the different stable states and the initial numbers of the different motor species that are bound to the track, the steady state of the cargo movement can be predicted, and consequently the steady state velocity can be obtained. It is found that, the velocity, even the direction, of the cargo movement change with the initial numbers of the motors which are bound to the track and several other parameters.