NLS-indepedent nucleocytoplasmic transport pathways of macromolecules

大分子通过核孔复合体(NPC)在细胞质和细胞核之间穿过核膜运输。转运底物与可溶性受体结合，随后通过能量和RAN依赖的机制通过NPC。RAN GTP酶调节底物与受体的结合和解离。最被理解的运输途径是含有核定位信号(NLS)的蛋白质进入细胞核。NLS受体由两个亚基组成(输入素-α和β)。其他更专业化的运输途径不依赖于进口。核糖体蛋白直接与各种重要的β受体结合。本项目的目的是研究核糖体蛋白的核输入，并分析导入蛋白-β相关受体在体内和体外核糖体蛋白输入中的作用。另一个目标是研究几种新的Importin-beta相关受体的功能。在这里，我们将重点放在识别各自的运输底物上。

Transport of macromolecules between the cytoplasm and the nucleus across the nuclear envelope occurs through the nuclear pore complex (NPC). Transport substrates bind to soluble receptors and subsequently pass the NPC by an energy- and Ran-dependent mechanism. The Ran GTPase regulates association and dissociation of the substrates with the receptors. The best understood transport pathway is the import of nuclear localization signal (NLS)-containing proteins into the nucleus. The NLS-receptor consists of two subunits (importin-alpha and beta). Other, more specialized transport pathways are not importin-dependent. Ribosomal proteins directly bind to various importinbeta-related receptors. The aim of this project is to investigate nuclear import of ribosomal proteins in general and to analyze the role of importin-beta-related receptors in ribosomal protein import in vivo and in vitro. Another goal is the functional characterization of several novel importin-beta-related receptors. Here, we focus on the identification of the respective transport substrates.