Determinants of molecular motor directionality.

Work over the past two years has led to a breakthrough in our understanding of the molecular basis of the directionality of the kinesin motor proteins. This breakthrough has come first from the reversal of directionality of the kinesin-related motor Ncd, followed closely by the reversal of kinesin's directionality and the finding that the Ncd 'neck' can convert Ncd or kinesin, which are intrinsically plus-end-directed microtubule motors, into a minus-end motor. These findings raise several outstanding questions, foremost, how does the neck function in motor directionality?