STRUCTURE AND FUNCTION OF CYTOPLASMIC MOTORS

本项目的目标是了解分布和功能 神经元轴突中的细胞质马达。 该信息 目的是在分子水平上， 和缓慢的轴突运输以及细胞质的组织， 轴突我们的研究结果表明，驱动蛋白更紧密地结合到 细胞器表面比动力蛋白导致的阐述简单的 转运方向取决于顺行囊泡结合的观点 驱动蛋白和逆行囊泡结合动力蛋白。 因为细胞器 能够在运输过程中保留其特定的驱动蛋白 轴突，我们认为驱动蛋白的上调或下调决定了 运输的方向。新型肌球蛋白马达已经被 被发现附着在鱿鱼轴突细胞器的表面， 现在看来，至少有两种肌球蛋白也参与其中， 在细胞器运输中。 我们已经开发出了针对这两种病毒的抗体 肌球蛋白，并且两种肌球蛋白都与细胞器相关。新研究 轴突中这些马达的肌动蛋白底物的组织 已经表明平行的肌动蛋白丝与微管相互交错 束，并且它们具有混合极性，这表明它们可能 携带细胞器进出微管束。 我们做了一个 从定义慢传输机制开始。负电荷 注射到鱿鱼巨大轴突中的大分子组装体在 以高达0.5 μ m/sec的速率沿顺行方向移动。 特别感兴趣的 是神经丝蛋白以及肌动蛋白和微管 碎片顺行移动，所有的运动似乎是沿着 某种类型的细胞内通道这个体外试验应该可以 可以限定用于这种运动的马达。 细菌 鞭毛马达在E.大肠杆菌作为另一个例子进行了研究， 运动系统比可以切换移位的方向。我们 完成对这种细胞质表达的结构研究， 电动机，预计将提供新的信息

The goal of this project is to understand the distribution and functions of cytoplasmic motors in the axon of neurons. This information is intended to lead to an understanding, at the molecular level, of fast and slow axonal transport as well as the cytoplasmic organization in the axon. Our results showing that kinesin is more tightly bound to organelle surfaces than dynein have led to elaboration of the simple idea that direction of transport depends on anterograde vesicles binding kinesin and retrograde vesicles binding dynein. Since an organelle could retain its particular kinesins while it is being transported down the axon, we propose that up or down regulation of kinesin determines the direction of transport. New types of myosin motors has been discovered attached to the surfaces of squid axonal organelles, and it now appears that there are at least two species of myosin also involved in organelle transport. We have developed antibodies to both of these myosins, and both myosins are associated with organelles. New studies of the organization of the actin substrates for these motors in the axon has showed that parallel actin filaments intertwine with the microtubule bundles, and that they have mixed polarities, suggesting that they might carry organelles both to and from the microtubule bundles. We made a start on defining the mechanism of slow transport. Negatively charged macromolecule assemblies injected into the squid giant axon move in the anterograde direction at rates up to 0.5 um/sec. Of particular interest is that neurofilament proteins as well as actin and microtubule fragments move anterogradely, and that all movements appear to be along some type of intracellular tract. This in vitro assay should make it possible to define the motors for such movements. The bacterial flagellar motor in E. coli has been studied as another example of a motor system than can switch direction of translocation. We are completing a structural study of the cytoplasmic representation of this motor which is expected to provide new information on the