Cytoplasmic microtubule sliding: An unconventional function of conventional kinesin.

There are well known examples in nature of microtubules dramatically changing their function by re-organizing their structure. Most interphase animal cells rely on the radial organization of the microtubule network for precise cargo delivery. Dividing cells re-organize microtubules with the help of motor proteins to form the spindle and drive the segregation of chromosomes into daughter cells. These examples present a kind of dichotomy: microtubules can be utilized as stationary tracks along which motor proteins move, or they can perform work themselves by utilizing the power of motor proteins. While both occur during mitosis, our recent findings demonstrate that both functions may occur simultaneously in interphase cells as well. We find that kinesin-1 (a motor known for its role in transporting cargo along microtubule tracks) powers microtubule sliding in non-dividing cells and this mechanism is used to form cellular protrusions.