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CRM1-mediated Recycling of Snurportin 1 to the Cytoplasm

  • Paraskeva, Efrosyni Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Izaurralde, Elisa Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Bischoff, F. Ralf Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Huber, Jochen Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Kutay, Ulrike Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Hartmann, Enno Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Lührmann, Reinhard Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
  • Görlich, Dirk Zentrum für Molekulare Biologie der Universität Heidelberg, D-69120 Heidelberg, Germany; University of Geneva, Department of Molecular Biology, CH-1211 Geneva 4, Switzerland; Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany; Institut für Molekularbiologie und Tumorforschung, D-35037 Marburg, Germany; and Zentrum Biochemie und Molekulare Zellb
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  • 1999-4-19
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  • Journal of Cell Biology. - Rockefeller University Press. - 1999, vol. 145, no. 2, p. 255-264
Cell Biology
English Importin β is a major mediator of import into the cell nucleus. Importin β binds cargo molecules either directly or via two types of adapter molecules, importin α, for import of proteins with a classical nuclear localization signal (NLS), or snurportin 1, for import of m3G-capped U snRNPs. Both adapters have an NH2-terminal importin β–binding domain for binding to, and import by, importin β, and both need to be returned to the cytoplasm after having delivered their cargoes to the nucleus. We have shown previously that CAS mediates export of importin α. Here we show that snurportin 1 is exported by CRM1, the receptor for leucine-rich nuclear export signals (NESs). However, the interaction of CRM1 with snurportin 1 differs from that with previously characterized NESs. First, CRM1 binds snurportin 1 50-fold stronger than the Rev protein and 5,000-fold stronger than the minimum Rev activation domain. Second, snurportin 1 interacts with CRM1 not through a short peptide but rather via a large domain that allows regulation of affinity. Strikingly, snurportin 1 has a low affinity for CRM1 when bound to its m3G-capped import substrate, and a high affinity when substrate-free. This mechanism appears crucial for productive import cycles as it can ensure that CRM1 only exports snurportin 1 that has already released its import substrate in the nucleus.
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  • English
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https://sonar.ch/global/documents/134127
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