FIGURE 9:

Schematic summarizing current model of polarity sorting mechanism in axons. (A) Control conditions. We predict that when dynein is the primary driver of MT movement, MTs are sorted according to their polarity orientation with plus-end-out MTs usually moving distal (to the right in the figure) and minus-end-out MTs (indicated with red dashed circles) being transported toward the cell body and cleared from the axon. We posit that static cross-linkers prevent movement of longer MTs, and that MTs are occasionally mis-sorted by plus-directed motors. (B) Dynein inhibition. Inhibition of dynein disrupts the polarity sorting mechanism by increasing the likelihood that a plus-directed motor such as kinesin-1 transports an MT in the “incorrect” direction, with its minus end leading (indicated with yellow dashed circles). (C) Cross-linker inhibition. When the density of static cross-linkers is depleted, this leads to increased mobility of longer MTs (indicated with orange dashed circles).