Architecture of the Diffusion Barrier in the Nuclear Pore Complex

核孔复合体(NPC)是最重要的分子之一。 真核生物中的机器，因为它把关了细胞质之间的多孔管道 和核质，并控制所有的核质运输和通讯。 它最重要的建筑特征是一种鲜为人知的半渗透性扩散 中央的屏障，对小到4岁的细胞质蛋白保持紧密的密封 尺寸为纳米级，但打开后可以方便地传输各种形状的颗粒 尺寸最大可达40纳米。这种灵活的屏障由一系列 名为FG核孔蛋白(FG NUP)的丝状蛋白质，其特征是大而未折叠 结构域处于其天然功能状态，由多个苯丙氨酸装饰 甘氨酸基序(FG结构域)。 我们提出的研究的具体目的是：1)描述动态 代表两种不同类型FG结构域的结构和分子内相互作用 锚定在NPC三个不同地点的FG NUP细丝，以及2)测试 假设NUP的FG结构域之间的分子间联系产生了一个 鼻咽癌中心的丝状网状结构，这建立了尺寸选择性 阻碍蛋白质被动扩散的障碍。拟议中的实验将结合 生化、生物物理、细胞生物学、结构(核磁共振)，以及 分子建模技术，以深入了解动态行为，结构和 FG NUPS的功能。我们还将获得有关动态的基本知识 蛋白质无序结构域的一般行为和结构。我们正在研究细胞蛋白质的三维结构，这些蛋白质的功能是 我们的遗传物质在细胞核中的守门人。他们适当的架构和 功能对人类健康至关重要，因为它们控制着进出的信息流 我们的基因。当它们不能正常发挥功能时，这些蛋白质可以触发 癌症。我们希望了解它们的结构是如何使它们发挥作用的 原子核的守门人。

The nuclear pore complex (NPC) is one of the most important molecular machines in eukaryotes because it gates the porous conduits between the cytoplasm and nucleoplasm of cells and controls all nucleo-cytoplasmic traffic and communication. Its most important architectural feature is a poorly understood semi-permeable diffusion barrier in its center that maintains a tight seal against cytoplasmic proteins as small as 4 nanometers in size, but opens to allow facilitated transport of particles of all shapes and sizes up to 40 nanometers in size. This flexible barrier is composed of a family of filamentous proteins named FG nucleoporins (FG nups) that feature large unfolded domains in their native functional state, which are decorated with multiple phenylalanine glycine motifs (FG domains). The specific aims of our proposed research are to 1) characterize the dynamic structure and intra-molecular interactions of FG domains representing two different types of FG nup filaments that are anchored at three different locales of the NPC, and 2) test the hypothesis that inter-molecular associations between FG domains of nups create a filamentous meshwork structure at the NPC center, which establishes the size-selective barrier to the passive diffusion of proteins. The proposed experiments will combine biochemical, biophysical, cell biological, structural (Nuclear Magnetic Resonance), and molecular modeling techniques to gain insight into the dynamic behavior, structure and function of the FG nups. We will also gain fundamental knowledge on the dynamic behavior and structure of disordered domains of proteins in general. We are studying the three-dimensional structure of the cellular proteins that function as gatekeepers of our genetic material in the nucleus. Their proper architecture and function is vital to human health because they control the flow of information to and from our genes. When they fail to function normally, these proteins can trigger the onset of cancer. We wish to understand how their structure enables them to function as gatekeepers of the nucleus.