From the ‡Department of Molecular Biology, Faculty of Medicine, Göttingen Center of Biosciences (GZMB), Georg-August-University Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
§Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Grisebachstr 8, 37077 Göttingen, Germany.
Mol Cell Proteomics. 2018 Jul;17(7):1337-1353. doi: 10.1074/mcp.RA118.000623. Epub 2018 Apr 17.
Importin 13 is a member of the importin β family of transport receptors. Unlike most family members, importin 13 mediates both, nuclear protein import and export. To search for novel importin 13 cargoes, we used stable isotope labeling of amino acids in cell culture (SILAC) and mass spectrometry. Using stringent criteria, we identified 255 importin 13 substrates, including the known cargoes Ubc9, Mago and eIF1A, and validate many of them as transport cargoes by extensive biochemical and cell biological characterization. Several novel cargoes can also be transported by the export receptor CRM1, demonstrating a clear redundancy in receptor choice. Using importin 13 mutants, we show that many of the novel substrates contact regions on the transport receptor that are not used by Ubc9, Mago or eIF1A. Together, this study significantly expands the repertoire of importin 13 cargoes and sets the basis for a more detailed characterization of this extremely versatile transport receptor.
Importin 13 是输入蛋白β家族的运输受体成员。与大多数家族成员不同，Importin 13 介导核蛋白的输入和输出。为了寻找新的 Importin 13 货物，我们使用了稳定同位素标记的细胞培养氨基酸（SILAC）和质谱法。使用严格的标准，我们鉴定了 255 种 Importin 13 底物，包括已知的货物 Ubc9、Mago 和 eIF1A，并通过广泛的生化和细胞生物学特性验证了其中许多作为运输货物。一些新的货物也可以被出口受体 CRM1 运输，这表明受体选择存在明显的冗余。使用 Importin 13 突变体，我们表明许多新的底物与 Ubc9、Mago 或 eIF1A 不使用的运输受体区域接触。总的来说，这项研究显著扩展了 Importin 13 货物的范围，并为这个极其多功能的运输受体的更详细特征奠定了基础。
