Figure 1.

Cartoon representation of motor proteins and vesicular cargo transport in the cell. Myosin family motors, myosin Va (dark brown) and myosin VI (light blue), walk along actin filaments (red) at the cortex. Myosin Va walks toward the F-actin plus-end, which is oriented towards the membrane. Myosin VI walks towards the minus-end of F-actin, toward the cell interior. Microtubule-based motors include the kinesin family motors (orange) and cytoplasmic dynein (violet). Kinesin motors walk to the plus-ends of microtubules (green), which are oriented toward the actin cortex. Dynein motors walk toward the minus-end of the microtubule, which is located at the microtubule-organizing center (MTOC, green) near the cell nucleus (blue). F-actin and microtubules cross at the cell cortex, as highlighted by black arrowheads (lower right). F-actin can cross itself in the cortex, highlighted by the red arrowheads (left). Microtubules can intersect other microtubules highlighted by the green arrowhead (center). Vesicular cargo (tan) can bind to myosin VI and dynein to switch from actin-based to microtubule-based motion while being transported into the cell interior (lower left). Vesicles can bind kinesin and myosin Va to switch from microtubule-based to actin-based motion in order to be transported to the cell cortex (lower right). Vesicles traveling on microtubules can experience a tug-of-war from kinesin and dynein simultaneously bound (right).