Ncd, a kinesin-related microtubule motor protein that moves the 'wrong' way on microtubules, towards the minus ends, has now been made to move like kinesin, towards plus ends, by fusing regions from outside the kinesin motor domain to the Ncd motor. Since it is the kinesin motor domain that binds to and moves on the microtubule, the finding that regions outside the motor domain can confer directionality of Ncd movement is remarkable-it implies a structural basis for motor polarity. Here we consider this finding from a structural point of view and discuss the implications for motor function and evolution.