meaurment of single molecules of motor proteins with angustrome rsolution

动力蛋白和驱动蛋白之间的结构差异预测（建议）一个独特的动力蛋白运动的分子机制。测量动力蛋白单分子的力学性质对于揭示其运动机制至关重要。我们测量的步长和力产生的单分子的活性细胞质动力蛋白使用的光学陷阱和荧光成像具有高的时间分辨率。动力蛋白的运动速度为800 nm/s，与细胞中报道的一致。最大作用力为7-8 pN，与ATP浓度无关，与驱动蛋白相似。动力蛋白表现出向前和偶尔向后的步骤为0.8nm，独立于负载。通过负染色电子显微镜观察动力蛋白显示环域部分重叠。肌球蛋白V是一个双头的进行性分子马达，它沿着沿着肌动蛋白丝以36 nm的步长运动。使用具有高时空分辨率的光阱纳米测量，我们发现36 nm的台阶有两种可能的路径，一种是12 nm和24 nm的子台阶，按照这个顺序，另一种没有子台阶。在分析ATP、ADP和2，3-丁二酮2-单肟对细胞增殖的影响的基础上，（这里显示的试剂减缓ADP从肌动球蛋白V释放）对主要和中间状态的停留时间和出现频率的影响，我们认为，12-nm的子步骤发生在ATP结合到结合的拖尾头部之后，24-nm的子步骤是由actornyosin异构化之后的机械步骤引起的。绑定的前导头上的ADP状态。当异构化先于12纳米子步骤时，36纳米步骤发生，没有子步骤。

Structural differences between dynein and kinesin predict (suggest) a unique molecular mechanism of dynein motility. Measuring the mechanical properties of single molecule of dynein is crucial to reveal the mechanisms underlying its movement. We measured the step size and force produced by single molecules of active cytoplasmic dynein using an optical trap and fluorescence imaging with a high temporal resolution. The velocity of dynein movement, 800 nm/s, is consistent with that reported in cells. The maximum force of 7-8 pN was independent of the ATP concentration and similar to that of kinesin. Dynein exhibited forward and occasional backwards steps of 〜8 nm, independent of load. Visualization of dynein by negative stain electron microscopy shows that the ring domains partially overlap. This indicates that the large dynein heads take 16-nm steps using an overlapping hand-over-hand mechanism.Myosin V is a double-headed processive molecular motor that moves along an actin filament by taking 36-nm steps. Using optical trapping nanometry with high spatiotemporal resolution, we discovered that there are two possible pathways for the 36-nm steps, one with 12- and 24-nm substeps, in this order, and the other without substeps. Based on the analyses of effects of ATP, ADP and 2,3-butanedione 2-monoxime (a reagent shown here to slow ADP release from actomyosin V) on the dwell time and the occurrence frequency of the main and the intermediate states, we propose that the 12-nm substep occurs after ATP binding to the bound trailing head and the 24-nm substep results from a mechanical step following the isomerization of an actornyosin-ADP state on the bound leading head. When the isomerization precedes the 12-nm substep, the 36-nm step occurs without substeps.