Studies on Microtubule Binding Proteins

描述（由申请人提供）：细胞通过一分为二而增加数量。每个子细胞接收母细胞一半的内容和相同的染色体副本-遗传指令。在准备分裂的过程中，染色体对被收集在纺锤形微管支架上。然后将这些对分离到主轴的两极。随后，两极进一步分离，染色体也随之分离，细胞膜收缩到纺锤体中平面，将细胞挤压成两个子细胞，每个子细胞都有一个精确的遗传物质拷贝和原始细胞质的一半。这个描述是一个非常复杂和严格管制的过程的一个大大简化的版本。微管是核心参与者;它们定义了基本的纺锤体结构，它们是引导染色体在各个阶段到达目的地的轨道，它们是分子马达用来在细胞质分裂之前将纺锤体两极分开的底物。这一过程对健康细胞和病变细胞都至关重要。由于癌细胞正在不受控制地分裂，纺锤体是抗癌药物的常见靶点。拟议的工作是一系列的结构测定，旨在可视化至关重要的蛋白质和大分子复合物如何在微管上的活动焦点相互作用。感兴趣的区域是微管的正负端。在这里，协调的微管组装和拆卸导致染色体收集，然后分离染色体对。特别令人感兴趣的是负责染色体附着到分解微管正末端的蛋白质，与正末端结合和跟踪的蛋白质，以及覆盖和保护负末端的蛋白质。另一个感兴趣的区域是纺锤体中心的区域，其中来自相反两极的微管重叠。在这里，交联蛋白和马达决定和调节纺锤体长度。将通过低温电子显微镜和图像分析进行结构测定。我们获得的结构结果将提供一些最重要的事件发生在纺锤体微管在细胞分裂过程中的机械理解的基础。

DESCRIPTION (provided by applicant): Cells increase in number by dividing in two. Each daughter cell receives half the contents of the mother cell and an identical copy of the chromosomes - the genetic instructions. During preparation for division, the chromosome pairs are collected on a spindle shaped microtubule scaffold. The pairs are then separated to the two poles of the spindle. Subsequently the poles move further apart, taking the chromosomes with them and the cell membrane constricts into the spindle midplane, pinching the cell into two daughters each with an exact copy of the genetic material and half of the cytoplasm of the original. This description is a greatly simplified version of a very complicated and tightly regulated process. The microtubules are the central players; they define the basic spindle architecture, they are the tracks that guide chromosomes to their destinations at the various stages and they are the substrates that molecular motors use to push the spindle poles apart before the cytoplasm is divided. The process is of fundamental importance for both healthy and diseased cells. As cancer cells are dividing uncontrollably, the spindle is a common target for anti-cancer drugs. The proposed work is a series of structure determinations aimed at visualizing how critically important proteins and macromolecular complexes interact at foci of activity on the microtubules. The regions of interest are the plus and minus ends of microtubules. Here coordinated microtubule assembly and disassembly result in chromosome collection followed by separation of the chromosome pairs. Of particular interest are proteins responsible for chromosome attachment to disassembling microtubule plus ends, proteins that bind and track with the plus ends and a protein that caps and protects minus ends. The other region of interest is the zone in the center of the spindle where microtubules from opposite poles overlap. Here crosslinking proteins and motors determine and regulate spindle length. The structure determinations will be carried out by cryo-electron microscopy and image analysis. The structural results we obtain will provide the basis for a mechanistic understanding of some of the most important events taking place on spindle microtubules during cell division.