deCastro M J, Fondecave R M, Clarke L A, Schmidt C F, Stewart R J
Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112, USA.
Nat Cell Biol. 2000 Oct;2(10):724-9. doi: 10.1038/35036357.
The ncd protein is a dimeric, ATP-powered motor that belongs to the kinesin family of microtubule motor proteins. Here we resolve single mechanochemical cycles of recombinant, dimeric, full-length ncd, using optical-tweezers-based instrumentation and a three-bead, suspended-microtubule assay. Under conditions of limiting ATP, isolated and transient microtubule-binding events exhibit exponentially distributed and ATP-concentration-dependent lifetimes. These events do not involve consecutive steps along the microtubule, quantitatively confirming that ncd is non-processive. At low loads, a single motor molecule produces ATP-triggered working strokes of about 9 nm, which occur at the ends of binding events.
Ncd蛋白是一种二聚体、由ATP供能的马达蛋白，属于驱动蛋白家族的微管马达蛋白。在此，我们使用基于光镊的仪器和三珠悬浮微管检测法，解析了重组二聚体全长Ncd的单个机械化学循环。在ATP受限的条件下，孤立且短暂的微管结合事件呈现指数分布且依赖于ATP浓度的寿命。这些事件不涉及沿微管的连续步骤，定量证实了Ncd是非持续性的。在低负载下，单个马达分子会产生约9纳米的ATP触发工作冲程，该冲程发生在结合事件的末端。
