Interactions and structure of the nuclear pore complex revealed by cryo-electron microscopy.
Interactions and structure of the nuclear pore complex revealed by cryo-electron microscopy.
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DOI：
10.1083/jcb.109.3.955
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发表时间：
1989-09
期刊：
影响因子：
--
通讯作者：
Akey CW
中科院分区：
文献类型：
--
作者：
Akey CW
核孔复合物（NPC）在真核细胞中介导核质转运和交换过程中起着重要作用。两栖动物核膜内的NPC的安排和相互作用进行了研究，使用冷冻电子显微镜的未固定和冷冻水化标本。Necturus的核纤层形成一个正交网络，交叉距离在1，600和4，000之间变化，这可能与核纤层的基本丝重复有关。此外，NPC随机附着在核纤层蛋白网络的范围内，可能是通过它们的核质环。洗涤剂提取的NPC的边缘和正面投影的图像分析已经与同轴细环上的数据相结合，以提供先前提出的NPC结构的三环模型的定量评估（Unwin，P.N. T.，和R.米利根1982. 93：63-75）。复杂的其他细节已被可视化，包括内部辐条域作为内部辐条环的紧密关联，辐条和同轴细环内的广泛域，以及有趣的是，中央通道状特征。膜相关的NPC和洗涤剂提取的NPC都具有位于外周的径向臂，导致有效直径约为1，450 - 1，500 A。在投影中，径向臂具有近似镜像对称性，表明它们源自组件的两侧。此外，膜相关的NPC在大多数半径处是不对称的，并且从细胞质观察是右旋的;去污剂提取的NPC似乎是对称的，并且具有大约822对称性。两者合计，数据表明，膜相关的NPC的框架是从一个对称的配置扰动，无论是在隔离的核或在体内与层和核膜的相互作用。然而，去污剂提取的核似乎导致组件在组装体的相对半部分中更对称的对齐。
Nuclear pore complexes (NPCs) play a central role in mediating nucleocytoplasmic transport and exchange processes in eukaryotic cells. The arrangement and interactions of NPCs within amphibian nuclear envelopes have been studied using cryo-electron microscopy of unfixed and frozen hydrated specimens. The nuclear lamina in Necturus forms an orthogonal network with crossover distances which vary between 1,600 and 4,000 A and which may be related to the basic filament repeat of lamins. Furthermore, the NPCs are attached randomly within the confines of the lamin network, presumably by their nucleoplasmic rings. Image analysis of edge-on and en face projections of detergent-extracted NPCs has been combined with data on the coaxial thin rings to provide a quantitative evaluation of the triple ring model of NPC architecture proposed previously (Unwin, P. N. T., and R. Milligan. 1982. J. Cell Biol. 93:63-75). Additional details of the complex have been visualized including an intimate association of the inner spoke domains as an inner spoke ring, extensive domains within the spokes and coaxial thin rings, and interestingly, a central channel-like feature. Membrane- associated NPCs and detergent-extracted NPCs both possess peripherally located radial arms resulting in an effective diameter of approximately 1,450-1,500 A. In projection, the radial arms possess approximate mirror symmetry suggesting that they originate from both sides of the assembly. Moreover, membrane-associated NPCs are asymmetric at most radii and right-handed as viewed from the cytoplasm; detergent- extracted NPCs appear to be symmetric and have approximately 822 symmetry. Taken together, the data suggests that the framework of membrane-associated NPCs is perturbed from a symmetrical configuration, either during isolation of nuclei or by interactions with the lamina and the nuclear envelope in vivo. However, detergent extraction of nuclei appears to result in a more symmetrical alignment of components in apposing halves of the assembly.