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

The collective behavior of molecular motor proteins have been investigated in the literature using models to describe the long-time dynamics of a unidimensional continuum motor distribution. Here, we consider the phenomena related to the transport of particles (vesicles, organelles, virus, etc) in the realm of these continuum motor systems. We argue that cargo movement may result from its ability to perturb the existing motor distribution and to surf at the resulting shock waves separating regions of different motor densities within the transient regime. In this case, the observed bidirectionality of cargo movement is naturally associated with reversals of shocks directions. Comparison of the quantitative results predicted by this model with available data for cargo velocity allows us to suggest that geometrical characteristics of the transported particle shall determine the extension and intensity of the perturbation it produces and thus, its dynamics. Possible implications of these ideas to virus movement at the cell body are discussed in connection with their distinguished morphological characteristics.