Ran GTPASE Regulation of the CRM1-Dependent Export Pathway

  • Bryce M. Paschal
  • Catherine Dargemont


Nuclear proteins that are not stably bound to intranuclear structures have the potential to be transported to the cytoplasm. Recent studies on proteins that undergo nuclear export led to the identification of cis-acting nuclear export signals or NES. These short sequence motifs are recognized by specific receptors, called karyopherins or exportins, which belong to a large family of proteins conserved through evolution. The NES, which in both cellular and viral proteins is enriched in hydrophobic amino acids including leucine, specifically interacts with the nuclear export receptor CRM1. The function of CRM1 is to mediate association with the nuclear pore complex and translocation of the NES protein to the cytoplasm. Binding of NES to CRM1 occurs in a Ran-GTP-dependent manner, but GTP hydrolysis is not required for this binding, or for translocation of the export complex through the NPC. CRM1 and Ran are sufficient to promote translocation of the cargo from the nucleoplasm to the cytoplasmic face of the nuclear pore complex, however, additional Ran·TP-binding proteins including the newly described NXT1 protein are also required to facilitate nuclear export. In the cytoplasm, dissociation of Ran from the export complex is triggered by the concerted action of different Ran regulatory proteins. These include the Ran GTPase Activating Protein, Ran Binding Proteins 1 and 2, and NXT1. Ran dissociation reverses the interactions between NES and CRM1, and CRM1 and the nuclear pore complex. Thus, disassembly of the nuclear export complex leads to the release of the NES-containing cargo in the cytoplasm and the recycling of CRM 1 back to the nucleus where it is available for a new round of transport. In this review, we describe what is known about the various steps in nuclear export of proteins and RNA-protein complexes by the CRM 1-dependent pathway, with special emphasis on the role of the Ran GTPase and associated proteins in this process.


Nuclear Export Nuclear Import Nuclear Pore Complex Nuclear Export Signal Nuclear Retention 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Adachi Y, Yanagida M (1989) Higher order chromosome structure is affected by cold sensitive mutations in a Schizosaccharomyces pombe gene crml+ which encodes a 115-kD protein preferentially localized in the nucleus and its periphery. J Cell Biol 108, 1195–1207PubMedCrossRefGoogle Scholar
  2. Askjaer P, Jensen TH, Nilsson J, Englmeier L, Kjems J (1998) The specificity of the CRM 1-Rev nuclear export signal interaction is mediated by RanGTP. J Biol Chem 273, 33414–33422PubMedCrossRefGoogle Scholar
  3. Askjaer P, Bachi A, Wilm M, Bischoff FR, Weeks DL, Ogniewski V, Ohno M, Niehrs C, Kjems J, Mattaj IW, Fornerod M (1999) RanGTP-regulated interactions of CRM1 with nucleoporins and a shuttling DEAD-box helicase. Mol Cell Biol 19, 6276–6285PubMedGoogle Scholar
  4. Bischoff FR, Ponstingl H (1991) Catalysis of guanine nucleotide exchange on Ran by the mitotic regulator RCC1. Nature 354, 80–82PubMedCrossRefGoogle Scholar
  5. Black BE, Levesque L, Holaska JM, Wood TC, Paschal BM (1999) Identification of an NTF2-related factor that binds Ran-GTP and regulates nuclear protein export. Mol Cell Biol 19, 8616–8624PubMedGoogle Scholar
  6. Black BE, Holska JM, Lévesque L, Ossareh-Nazari B, Gwizdek C, Dargemont C, Paschal BM (2001) NXT1 is necessary for the terminal step of Crml-mediated nuclear export. J Cell Biol 152, 141–156PubMedCrossRefGoogle Scholar
  7. Borer RA, Lehner CF, Eppenberger HM, Nigg EA (1989) Major nucleolar proteins shuttle between nucleus and cytoplasm. Cell 56, 379–390PubMedCrossRefGoogle Scholar
  8. Coutavas E, Ren M, Oppenheim JD, D’Eustachio P, Rush MG (1993) Characterization of proteins that interact with the cell-cycle regulatory protein Ran/TC4. Nature 366, 585–587PubMedCrossRefGoogle Scholar
  9. Dargemont C, Schmidt-Zachmann MS, Kuhn LC (1995) Direct interaction of nucleoporin p62 with mRNA during its export from the nucleus. J Cell Sci 108, 257–263PubMedGoogle Scholar
  10. Englmeier L, Olivo JC, Mattaj IW (1999) Receptor-mediated substrate translocation through the nuclear pore complex without nucleotide triphosphate hydrolysis. Curr Biol 9, 30–41PubMedCrossRefGoogle Scholar
  11. Fantozzi, DA, Harootunian AT, Wen W, Taylor SS, Feramisco JR, Tsien RY, Meinkoth JL (1994) Thermostable inhibitor of cAMP-dependant protein kinase enhance the rate of export the kinase catalytic subunit from the nucleus. J Biol Chem 269, 2676–2686PubMedGoogle Scholar
  12. Featherstone C, Darby MK Gerace L (1988) A monoclonal antibody against the nuclear pore complex inhibits nucleocytoplasmic transport of protein and RNA in vivo. J Cell Biol 107, 1289–1297PubMedCrossRefGoogle Scholar
  13. Finlay DR, Meier E, Bradley P, Horecka J, Forbes DJ (1991) A complex of nuclear pore proteins required for pore function. J. Cell Biol 114, 169–183PubMedCrossRefGoogle Scholar
  14. Fischer U, Huber J, Boelens WC, Mattaj IW, Luhrmann R (1995) The HIV-1 Rev activation domain is a nuclear export signal that accesses an export pathway used by specific cellular RNAs. Cell 82, 475–483PubMedCrossRefGoogle Scholar
  15. Floer M, Blobel G (1999) Putative reaction intermediates in Crml-mediated nuclear protein export. J. Biol Chem 274, 16279–16286PubMedCrossRefGoogle Scholar
  16. Fornerod M, Ohno M, Yoshida M, Mattaj IW (1997a) CRM1 is an export receptor for leucine-rich nuclear export signals. Cell 90, 1051–1060CrossRefGoogle Scholar
  17. Fornerod M, van Deursen J, van Baal S, Reynolds A, Davis D, Murti KG, Fransen J, Gros-veld G (1997b) The human homologue of yeast CRM1 is in a dynamic subcomplex with CAN/Nup214 and a novel nuclear pore component Nup88. EMBO J 16, 807–816CrossRefGoogle Scholar
  18. Fukuda M, Asano S, Nakamura T, Adachi M, Yoshida M, Yanagida M, Nishida E (1997) CRM1 is responsible for intracellular transport mediated by the nuclear export signal. Nature 390, 308–311PubMedCrossRefGoogle Scholar
  19. Goldstein L (1958) Localization of nucleus-specific protein as shown by transplantation experiments in Amoebœ proteus. Exp Cell Res 15, 635–637PubMedCrossRefGoogle Scholar
  20. Guan T, Kehlenbach RH, Schirmer EC, Kehlenbach A, Fan F, Clurman BE, Arnheim N, Gerace L (2000) Nup50, a nucleoplasmically oriented nucleoporin with a role in nuclear protein export. Mol Cell Biol 20, 5619–5630PubMedCrossRefGoogle Scholar
  21. Guzik BW, Levesque L, Prasad S, Bor YC, Black BE, Paschal BM, Rekosh D, Ham-marskjold ML (2001) NXT1 (pi5) is a crucial cellular cofactor in TAP-dependent export of intron-containing RNA in mammalian cells. Mol. Cell. Biol. 21, 2545–2554PubMedCrossRefGoogle Scholar
  22. Harootunian AT, Adams SR, Wen W, Meinkoth JL, Taylor SS, Tsien RY (1993) Movement of the free catalytic subunit of cAMP-dependent protein kinase into and out of the nucleus can be explained by diffusion. Mol Biol Cell 4, 993–1002PubMedGoogle Scholar
  23. Hopper AK, Traglia HM, Dunst RW (1990) The yeast RNA1 gene product necessary for RNA processing is located in the cytosol and apparently excluded from the nucleus. J Cell Biol 111, 309–321PubMedCrossRefGoogle Scholar
  24. Kaffman A, O’Shea EK (1999) Regulation of nuclear localization: a key to a door, Annu Rev Cell Dev Biol 75, 291–339CrossRefGoogle Scholar
  25. Katahira J, Strasser K, Podtelejnikov A, Mann M, Jung JU, Hurt E (1999) The Mex67p-mediated nuclear mRNA export pathway is conserved from yeast to human. EMBO J 18, 2593–2609PubMedCrossRefGoogle Scholar
  26. Kehlenbach RH, Dickmanns A, Gerace L (1998) Nucleocytoplasmic shuttling factors including Ran and CRM1 mediate nuclear export of NFAT in vitro. J Cell Biol 141, 863–874PubMedCrossRefGoogle Scholar
  27. Kehlenbach RH, Dickmanns A, Kehlenbach A, Guan T, Gerace L (1999) A role for RanBPl in the release of CRM1 from the nuclear pore complex in a terminal step of nuclear export. J Cell Biol 145, 645–657PubMedCrossRefGoogle Scholar
  28. Kraemer DM, Strambio-de-Castillia C, Blobel G, Rout MP (1995) The essential yeast nu-cleoporin NUP159 is located on the cytoplasmic side of the nuclear pore complex and serves in karyopherin-mediated binding of transport substrate. J Biol Chem. 270, 19017–19021PubMedCrossRefGoogle Scholar
  29. Kudo N, Matsumori N, Taoka H, Fujiwara D, Schreiner EP, Wolff B, Yoshida M, Hori-nouchi S (1999) Leptomycin B inactivates CRM 1/exportin 1 by covalent modification at a cysteine residue in the central conserved region. Proc Natl Acad Sci USA 96, 9112–9117PubMedCrossRefGoogle Scholar
  30. Madan AP, DeFranco DB (1993) Bidirectional transport of glucocorticoid receptors across the nuclear envelope. Proc Natl Acad Sci USA 90, 3588–3592PubMedCrossRefGoogle Scholar
  31. Mahajan R, Delphin C, Guan T, Gerace L, Melchior F (1997) A small ubiquitin-related polypeptide involved in targeting Ran GAPl to nuclear pore complex protein RanBP2. Cell 88, 97–107PubMedCrossRefGoogle Scholar
  32. Mattaj IW, Englmeier L (1998) Ncleocytoplasmic Transport: The Soluble Phase. Annu Rev Biochem 67, 265–306PubMedCrossRefGoogle Scholar
  33. Matunis MJ, Wu J, Blobel G (1998) SUMO-1 modification and its role in targeting the Ran GTPase-activating protein, RanGAPl, to the nuclear pore complex. J Cell Biol 140, 499–509PubMedCrossRefGoogle Scholar
  34. Meier UT Blobel G (1992) Noppl40 shuttles on tracks between nucleolus and cytoplasm. Cell 70, 127–138PubMedCrossRefGoogle Scholar
  35. Melchior F, Guan T, Yokoyama N, Nishimoto T, Gerace L (1995) GTP hydrolysis by Ran occurs at the nuclear pore complex in an early step of protein import. J Cell Biol 131, 571–581PubMedCrossRefGoogle Scholar
  36. Meyer BE, Malim MH (1994) The HIV-1 Rev trans-activator shuttles between the nucleus and the cytoplasm. Genes Dev 8, 1538–1547PubMedCrossRefGoogle Scholar
  37. Michael WM, Choi M, Dreyfuss G (1995) A nuclear export signal in hnRNP Al: a signal-mediated, temperature-dependent nuclear protein export pathway. Cell 83, 415–422PubMedCrossRefGoogle Scholar
  38. Michael WM, Eder PS, Dreyfuss G (1997) The K nuclear shuttling domain: a novel signal for nuclear import and nuclear export in the hnRNP K protein. EMBO J 16, 3587–3598PubMedCrossRefGoogle Scholar
  39. Mueller L, Cordes VC, Bischoff FR, Ponstingl H (1998) Human RanBP3, a group of nuclear RanGTP binding proteins. FEBS Letters 427, 330–336PubMedCrossRefGoogle Scholar
  40. Nakielny S, Dreyfuss G (1996) The hnRNP C proteins contain a nuclear retention sequence that can override nuclear export signals. J Cell Biol 134, 1365–1373PubMedCrossRefGoogle Scholar
  41. Nakielny S, Shaikh S, Burke B, Dreyfuss G (1999) Nupl53 is an M9-containing mobile nucleoporin with a novel Ran-binding domain. EMBO J 18, 1982–1995PubMedCrossRefGoogle Scholar
  42. Neville M, Stutz F, Lee L, Davis LI, Rosbash M (1997) The importin-beta family member Crmlp bridges the interaction between Rev and the nuclear pore complex during nuclear export. Curr Biol 7, 767–775PubMedCrossRefGoogle Scholar
  43. Nishi K, Yoshida M, Fujiwara D, Nishikawa M, Horinouchi S, Beppu T (1994) Leptomycin B targets a regulatory cascade of CRMl, a fission yeast nuclear protein, involved in control of higher order chromosome structure and gene expression. J Biol Chem 269, 6320–6324PubMedGoogle Scholar
  44. Ossareh-Nazari B, Dargemont C (1999) Domains of Crml involved in the formation of the Crml, RanGTP, and leucine-rich nuclear export sequences trimeric complex. Exp Cell Res 252, 236–241PubMedCrossRefGoogle Scholar
  45. Ossareh-Nazari B, Bachelerie F, Dargemont C (1997) Evidence for a role of CRM1 in signal-mediated nuclear protein export. Science 278, 141–144PubMedCrossRefGoogle Scholar
  46. Ossareh-Nazari B, Maison C, Black BE, Levesque L, Paschal BM, Dargemont C (2000) RanGTP-binding protein NXT1 facilitates nuclear export of different classes of RNA in vitro. Mol Cell. Biol 20, 4562–4571PubMedCrossRefGoogle Scholar
  47. Pante N, Aebi U (1995) Exploring nuclear pore complex structure and function in molecular detail. J Cell Sci (Suppl) 19, 1–11Google Scholar
  48. Paraskeva E, Izaurralde E, Bischoff FR, Huber J, Kutay U, Hartmann E, Luhrmann R, Görlich D (1999). CRM 1-mediated recycling of snurportin 1 to the cytoplasm, J. Cell Biol 145, 255–64.PubMedCrossRefGoogle Scholar
  49. Piflol-Roma S, Dreyfuss G (1992) Shuttling of pre-mRNA binding proteins between nucleus and cytoplasm. Nature 355, 730–732CrossRefGoogle Scholar
  50. Quimby B, Lamitina T, L’hernault S, Corbett AH (2000) The mechanism of Ran import into the nucleus by nuclear factor 2. J Biol Chem 15, 28575–28582CrossRefGoogle Scholar
  51. Radu A, Moore MS, Blobel G (1995) The peptide repeat domain of nucleoporin Nup98 functions as a docking site in transport across the nuclear pore complex. Cell 81, 215–222PubMedCrossRefGoogle Scholar
  52. Rexach M, Blobel G (1995) Protein import into nuclei: association and dissociation reactions involving transport substrate, transport factors, and nucleoporins. Cell 83, 683–692PubMedCrossRefGoogle Scholar
  53. Ribbeck K, Lipowsky G, Kent HM, Stewart M, Görlich D (1998) NTF2 mediates nuclear import of Ran. EMBO J 17, 6587–6598PubMedCrossRefGoogle Scholar
  54. Richards SA, Lounsbury KM, Carey KL, Macara, IG (1996) A nuclear export signal is essential for the cytosolic localization of the Ran binding protein, RanBPl. J Cell Biol 134, 1157–1168PubMedCrossRefGoogle Scholar
  55. Richards SA, Carey KL, Macara IG (1997) Requirement of guanosine triphosphate-bound ran for signal-mediated nuclear protein export. Science 276, 1842–1844PubMedCrossRefGoogle Scholar
  56. Rout MP, Aitchison JD, Suprapto A, Hjertaas K, Zhao Y, Chait BT (2000) The yeast nuclear pore complex: composition, architecture, and transport mechanism. J Cell Biol 148, 635–651PubMedCrossRefGoogle Scholar
  57. Schmidt-Zachmann MS, Dargemont C, Kuhn LC, Nigg, EA (1993) Nuclear export of proteins: the role of nuclear retention. Cell 74, 493–504PubMedCrossRefGoogle Scholar
  58. Singh BB, Patel HH, Roepman R, Schick D, Ferreira PA (1999) The zinc finger cluster domain of RanBP2 is a specific docking site for the nuclear export factor, exportin-1. J Biol Chem 274, 37370–37378PubMedCrossRefGoogle Scholar
  59. Smith A, Brownawell A, Macara IG (1998) Nuclear import of Ran is mediated by the transport factor NTF2. Curr Biol 8, 1403–1406PubMedCrossRefGoogle Scholar
  60. Stade K, Ford CS, Guthrie C, Weis K (1997) Exportin 1 (Crmlp) is an essential nuclear export factor. Cell 90, 1041–1050PubMedCrossRefGoogle Scholar
  61. Steggerda SM, Black BE, Paschal BM (2000) Monoclonal antibodies to NTF2 inhibit nuclear protein import by preventing nuclear translocation of the GTPase Ran. Mol Biol Cell 77,703–719Google Scholar
  62. Stoffler D, Fahrenkrog B, Aebi U (1999) The nuclear pore complex: from molecular architecture to functional dynamics. Curr Opin Cell Biol 77, 391–401CrossRefGoogle Scholar
  63. Strahm Y, Fahrenkrog B, Zenklusen D, Rychner E, Kantor J, Rosbach M., Stutz F (1999) The RNA export factor Glelp is located on the cytoplasmic fibrils of the NPC and physically interacts with the FG-nucleoporin Riplp, the DEAD-box protein Rat8p/Dbp5p and a new protein Ymr 255p. EMBO J 18, 5761–5777PubMedCrossRefGoogle Scholar
  64. Sukegawa J, Blobel G (1993) A nuclear pore complex protein that contains zinc finger motifs, binds DNA, and faces the nucleoplasm. Cell 72, 29–38PubMedCrossRefGoogle Scholar
  65. Taura T, Krebber H, Silver PA (1998) A member of the Ran-binding protein family, Yrb2p, is involved in nuclear protein export. Proc Natl Acad Sci USA 95, 7427–7432PubMedCrossRefGoogle Scholar
  66. Wen W, Meinkoth JL, Tsien RY, Taylor SS (1995) Identification of a signal for rapid export of proteins from the nucleus. Cell 82, 463–473PubMedCrossRefGoogle Scholar
  67. Wolff B, Sanglier JJ, Wang Y (1997) Leptomycin B is an inhibitor of nuclear export: inhibition of nucleo-cytoplasmic translocation of the human immunodeficiency virus type 1 (HIV-1) Rev protein and Rev-dependent mRNA. Chem Biol 4, 139–147PubMedCrossRefGoogle Scholar
  68. Wu J, Matunis MJ, Kraemer D, Blobel G, Coutavas E (1995) Nup358, a cytoplasmically exposed nucleoporin with peptide repeats, Ran-GTP binding sites, zinc fingers, a cyclo-philin A homologous domain, and a leucine-rich region. J Biol Chem 270, 14209–14213PubMedCrossRefGoogle Scholar
  69. Yaseen NR, Blobel G (1999) Two distinct classes of Ran-binding sites on the nucleoporin Nup-358. Proc Natl Acad Sci USA 96, 5516–5521PubMedCrossRefGoogle Scholar
  70. Yokoyama N, Hayashi N, Seki T, Pante N, Ohba T, Nishii K, Kuma K, Hayashida T, Miyata T, Aebi U, Fukui M, Nishimoto T (1995) A giant nucleopore protein that binds Ran/TC4. Nature 376, 184–188.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • Bryce M. Paschal
    • 1
  • Catherine Dargemont
    • 2
  1. 1.Center for Cell Signaling, Department of Biochemistry and Molecular GeneticsUniversity of VirginiaCharlottesvilleUSA
  2. 2.Institut Jacques Monod, UMR 7592ParisFrance

Personalised recommendations