Architecture of the Diffusion Barrier in the Nuclear Pore Complex

核孔复合物（NPC）是一种重要的生物分子， 在真核生物中是一种机器，因为它控制着细胞质之间的多孔管道， 和细胞核质，并控制所有的核质运输和通信。 其最重要的建筑特征是一个鲜为人知的半渗透扩散 在它的中心有一个屏障，对小到4 纳米大小，但开放，以允许所有形状的颗粒， 尺寸可达40纳米。这种柔性屏障由一系列 称为FG核孔蛋白（FG nups）的丝状蛋白，其特征在于大的未折叠的 结构域在其天然功能状态下，其被多个苯丙氨酸修饰 甘氨酸基序（FG结构域）。 我们提出的研究的具体目标是：1）表征动态 代表两种不同类型的FG结构域的结构和分子内相互作用 固定在NPC的三个不同部位的FG nup细丝，以及2）测试 nups的FG结构域之间的分子间缔合产生一种 在NPC中心的丝状网状结构，这建立了大小选择性 蛋白质被动扩散的屏障。拟议的实验将联合收割机 生物化学、生物物理学、细胞生物学、结构（核磁共振），以及 分子模拟技术，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行为和结构。我们正在研究细胞蛋白质的三维结构， 细胞核中遗传物质的守门人。它们的结构和 功能对人类健康至关重要，因为它们控制着信息的流动， 我们的基因当它们不能正常发挥功能时，这些蛋白质会引发 癌我们希望了解它们的结构如何使它们能够发挥作用， 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.