CORE ASSEMBLY OF THE NUCLEAR PORE COMPLEX

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 核被膜是真核细胞中将细胞核与细胞质分隔开的双层膜。NE被核孔复合物（NPC）穿孔，核孔复合物构成进出核的唯一通道。NPC是由数百个多肽组成的非常大的蛋白质组装体，估计质量为60-80 MDa。总的来说，NPC目前不适合X射线晶体学分析，因为它不能以足够大和纯的量生产。在我们的方法中，我们利用了NPC是高度模块化结构的事实。模块性反映在四个层面：1）NPC具有八重旋转对称性; 2）它由一组有限的约30种蛋白质组成，称为核孔蛋白或nup，以8的倍数出现; 3）nup组织在生物化学定义的离散子复合物中; 4）单个nup主要由少量结构域组成。利用这种高水平的模块化，我们正在努力阐明那些构成NPC核心支架的亚复合物。我们将结合联合收割机高分辨率的X射线结构与电子显微镜图像，以创建比目前可用的详细程度高得多的复合模型。这些模型将提供一种手段，在分子水平上解开NPC的功能原理。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The nuclear envelope is a double-layered membrane that separates the nucleus from the cytoplasm in the eukaryotic cell. The NE is perforated by nuclear pore complexes (NPCs) which constitute the only gateway into and out of the nucleus. The NPC is a very large protein assembly composed of several hundred polypeptides and an estimated mass of 60-80 MDa. As a whole, the NPC is currently not amenable to X-ray crystallographic analysis since it cannot be produced in large enough and pure quantities. In our approach, we exploit the fact that the NPC is a highly modular structure. The modularity is reflected in four layers: 1) the NPC has an eight-fold rotational symmetry; 2) it is composed of a limited set of about 30 proteins, called nucleoporins or nups, that occur in multiples of eight; 3) Nups are organized in discrete subcomplexes that are biochemically defined; 4) Individual nups are largely composed of a small number of structural domains. Exploiting this high level of modularity we are working on the elucidation of those subcomplexes that make up the core scaffold of the NPC. We will combine high-resolution X-ray structures with electron-microscopic images to create composite models of substantially higher level of detail than currently available. Such models will provide a means to unravel the functional principles of the NPC on a molecular level.