Molecular motor proteins serve as an essential component of intracellular transport by generating forces to haul cargoes along cytoskeletal filaments. In some circumstances, two species of motors that are directed oppositely (e.g. kinesin, dynein) can be attached to the same cargo . The resulting net motion is known to be bidirectional , but the mechanism of switching remains unclear. In this work , we propose a mean-field mathematical model of the mechanical interactions of two populations of molecular motors with diffusion of the cargo (thermal fluctuations ) as the fundamental noise source. By studying a simplified model, the delayed response of motors to rapid fluctuations in the cargo  is quantified, allowing for the reduction of the full model to two "characteristic positions " of each of the motor populations . The system is then found to be "metastable", switching between two distinct directional transport states , or bidirectional motion . The time to switch between these states is then investigated using WKB analysisin the weak-noise limit .
Molecular motor proteins serve as an essential component of intracellular transport by generating forces to haul cargoes along cytoskeletal filaments. Two species of motors that are directed oppositely (e.g. kinesin, dynein) can be attached to the same cargo , which is known to produce bidirectional net motion. However, the mechanism of switching remains subtle. Although previous work focuses on the motor number as the driving noise source for switching, this work proposes an alternative possibility: cargo diffusion. A mean-field mathematical model of mechanical interactions of two populations of molecular motors with cargo thermal fluctuations (diffusion) is presented to study this phenomenon. The delayed response of a motor to fluctuations in the cargo velocity is quantified, allowing for the reduction of the full model a single "characteristic position " , a proxy for the net force on the cargo . The system is then found to be metastable, with switching exclusively due to cargo diffusion between two distinct directional transport states . The time to switch between these states is then investigated using a mean first passage time analysis. The switching time is found to be non-monotonic in the drag of the cargo, providing an experimental prediction for verification .
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