Cytoplasmic dynein is the major motor protein that transports cargoes toward the minus end of microtubules. In most cell types, this corresponds to movement toward the cell interior. However, if dynein only moves to the minus end of microtubules, a problem arises: how would dynein initially reach the plus end of the microtubule and the outskirts of the cell, where it collects cargoes? In a recent eLIFE article, the Reck-Peterson Lab reveals that a group of three proteins can solve this problem by transporting dynein to the plus end of the microtubule. The proteins comprise a plus-end-directed kinesin motor, and two additional proteins that connect dynein to the kinesin. Imaging the transport process shows that the dynein motor is not a passive passenger: it is able to resist against the kinesin. However, an additional microtubule-associated protein can help the kinesin motor to win this “tug of war”, and so the protein complex—including the dynein motor—moves toward the plus end of the microtubule.
Figure: Kymograph showing a fluorescently labeled dynein construct (green) moving toward the plus end of the microtubule.