STRUCTURE AND FUNCTION OF CYTOPLASMIC MOTORS

本项目的目标是了解它们的分布和功能 神经元轴突中的细胞质马达。此信息是 旨在导致在分子水平上理解FAST和 缓慢的轴突运输以及细胞质的组织 轴突。这是该科的中心项目，一直非常 今年取得了丰硕的成果，提供了大量新发现。一本小说 鱿鱼轴突表面肌球蛋白II样马达亚类 细胞器已被发现，这种肌球蛋白及其钙调蛋白- LIKE轻链现在可以从大脑中大量纯化，并正在 特色化的。免疫标记显示该肌球蛋白与 轴突细胞器的表面。肌动蛋白的组织 轴突中这些马达的底物显示，肌动蛋白细丝 与微管束缠绕在一起。一种可能对以下方面有用的分析 关于确定慢化机制的难题的探讨 还引入了交通工具。注射的大分子组件 进入鱿鱼的巨型轴突以较快的速度顺行移动 最高可达0.5毫米/秒。特别令人感兴趣的是短肌动蛋白细丝 也是顺行移动的，所有的移动似乎都是沿着一些 胞内束的类型。这种体外试验应该会使这一点成为可能 来定义这种运动的马达。细菌鞭毛马达 在大肠杆菌中被研究为另一个马达系统的例子 转换易位的方向。冬虫夏草的一种新的细胞质成分 被认为与方向转换有关的鞭毛马达现在 已经被分离和提纯，我们在设计一种 马达这个组件中的蛋白质是如何构成的结构模型 有条理的。

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. This is the central project in the Section, and has been very productive this year, providing a plethora of new findings. A novel subclass of myosin II-like motors on the surfaces of squid axonal organelles has been discovered and this myosin as well as its calmodulin- like light chain can now be purified in quantity from brain, and is being characterized. Immunolabeling shows that this myosin adheres strongly to the surfaces of axonal organelles. The organization of the actin substrates for these motors in the axon has showed that actin filaments intertwine with the microtubule bundles. An assay that may be useful for approaching the difficult problem of defining the mechanism of slow transport has also been introduced. Macro-molecular assemblies injected into the squid giant axon are move in the anterograde direction at rates up to 0.5 Mm/sec. Of particular interest is that short actin filaments also 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. A new cytoplasmic component of the flagellar motor thought to be involved in directional switching has now been isolated and purified, and we are making progress in devising a structural model of how the proteins in this component of the motor are organized.