Structures and mechanisms of nuclear import and export

描述（由申请方提供）：核转运蛋白通过识别不同的核定位或输出信号（NLS或NES）介导核质转运。虽然在人类中有19种已知的Kap，但目前仅分别已知Kapα/Kapß 1、Kapß 2（或转运蛋白）和CRM 1的三类信号。大多数其他Kaps识别遮蔽其信号的身份的不同序列。该提案描述了输入系统Kapß 2和Imp 5/Kap 121以及输出-Kap CRM 1的结构和生化分析。Kapß 2通过RNA结合蛋白介导RNA结合蛋白的核输入。 PY-NLS。我们对PY-NLS的发现和理解有助于发现导致肌萎缩侧索硬化症（ALS）的一个子集的缺陷PY-NLS。在这里，我们建议了解Kapß 2在ALS中蛋白质错误定位和聚集中的作用。在另一个目标中，我们将应用我们用于发现PY-NLS的组合结构，生物化学和生物信息学方法到Imp 5/Kap 121 p通路，目的是发现一组特征以统一Kaps识别的不同序列，从而揭示一类新的NLS。最后，我们将研究CRM 1，它介导数百种蛋白质的核输出;其中大多数是使用小分子抑制剂Leptomycin B鉴定的。该提议旨在确定CRM 1如何介导来普霉素B缀合以抑制核输出的机制。

DESCRIPTION (provided by applicant): Karyopherinß proteins mediate nucleocytoplasmic transport through recognition of distinct nuclear localization or export signals (NLSs or NESs). Although there are 19 known Kaps in humans, only three classes of signals for Kapα/Kapß1, Kapß2 (or Transportin) and CRM1, respectively, are known at this time. Most other Kaps recognize diverse sequences that occlude the identity of their signals. This proposal describes structural and biochemical analyses of import systems Kapß2 and Imp5/Kap121 as well as the export-Kap CRM1. Kapß2 mediates nuclear import of RNA binding proteins through their PY-NLSs. Our discovery and understanding of the PY-NLS contributed to the discovery of a defective PY-NLS that causes a subset of amyotrophic lateral sclerosis (ALS). Here, we propose to understand the role of Kapß2 in protein mislocalization and aggregation in ALS. In another aim, we will apply the combined structural, biochemical and bioinformatics approach that we used to discover the PY-NLS to the Imp5/Kap121p pathway with the goal of discovering a set of characteristics to unify the diverse sequences recognized by the Kaps, hence revealing a new class of NLS. Finally, we will study CRM1, which mediates nuclear export of hundreds of proteins; most of them identified using the small molecule inhibitor Leptomycin B. This proposal aims to determine the mechanism of how CRM1 mediates conjugation of leptomycin B to inhibit nuclear export.