Modeling Motor-Assisted Intracellular Cargo Transport

Modeling Motor-Assisted Intracellular Cargo Transport

Michael Loewenberg, Jennifer Pascal, Arnaud Chauviere, Vittorio Cristini

Yale University, New Haven, CT, USA

University of New Mexico, Albuquerque, NM, USA

Intracellular transport of cargo, including macromolecules, vesicles and organelles, through the attachment to microtubules via molecular motors, such as kinesin and dynein, is a complex process that plays a significant role in cellular function.  Here, we present an analysis and experimental validation of the unidirectional traffic-type partial differential equations that describe motor-assisted intracellular cargo transport (Smith and Simmons 2001). A new analytical solution is obtained for the case of a single type of molecular motor.  The solution exhibits wave-like hyperbolic behavior at short times and a convective/diffusive behavior at longer times.  The long-time behavior is characterized by two parameters: the mean velocity of the cargo and a dispersion coefficient that results from the saltatory mechanism by which cargo binds and unbinds from the motors. The solution and thus the traffic-type model is tested using stochastic sampling of nanoparticle trajectories in the squid giant axon (doi 10.1088/1478-3975/9/5/055005).  We present a generalized analysis of motor-assisted cargo transport for an arbitrary number of motors, providing numerical results and analytical formulas that describe the long-time evolution of the system.