Kinesin is a protein motor that ferries membrane-bound packages around cells — but only in one direction. Forcing it into reverse provides clues to its inner workings and to how molecular machines might be engineered. Kinesin can carry a packet of neurotransmitter from your spine to the tip of your finger in about two days — a journey that would take a thousand years if left to simple diffusion. This molecular motor 'steps' along the micro-tubules that form the cytoskeletal scaffolding of cells, byconverting chemical energy into mechanical work. Carter and Cross (page 308 of this issue) probe the stepping behaviour of kinesin by using optical tweezers to push and pull on a single kinesin molecule attached to a small plastic bead. When they pulled strongly enough, kinesin could be made to walk backwards in a sustained manner. This dramatic result could provide the basis for developing a motor to drive nanoscale molecular machines.
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机译：驱动蛋白是一种蛋白质运动蛋白，可将膜结合的包裹运送到细胞周围，但只能在一个方向上运送。迫使其反向运行提供了有关其内部工作原理以及如何设计分子机器的线索。驱动蛋白可以在大约两天的时间内将一包神经递质从您的脊椎传送到您的指尖-如果仅进行简单扩散，则将花费一千年。这种分子马达通过将化学能转化为机械功，沿着形成细胞骨架的微管“运动”。 Carter and Cross（本期第308页）通过使用光镊推动和拉动附着在小塑料珠上的单个驱动蛋白分子，探索驱动蛋白的步进行为。当他们足够强地拉动时，驱动蛋白可以持续地向后走。这一惊人的结果可以为开发驱动纳米级分子机器的电动机提供基础。
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