Surfing at wave fronts: The bidirectional movement of cargo particles driven by molecular motors

We examine the properties of intracellular transport of particles (vesicles, organelles, virus, etc.) in the realm of models that describe the dynamics of interacting molecular motors moving along microtubules. We use a continuum description of motor distribution and argue that certain features of cargo movement have their origins on its ability to perturb the existing motor profile and to surf at the resulting shock wave fronts that separate regions of different motor concentrations. In this case, the observed bidirectionality of cargo movement is naturally associated with reversals of shock direction. Comparison of the quantitative results predicted by this model with available data suggests that the geometrical characteristics of cargo may be related to the extension and intensity of the perturbation they produce and thus, to their kinetics. Possible implications of these ideas to understand features of the movement of virus particles within the cell body are discussed in connection with their distinguished morphological characteristics.