The nuclear pore complex: From molecular architecture to functional dynamics

Current Opinion in Cell Biology

Volumn 11, Issue 3, 1999, Pages 391-401

  Stoffler, Daniel ^a   Fahrenkrog, Birthe ^a   Aebi, Ueli ^a  

^a UNIVERSITY OF BASEL   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

ADENOSINE TRIPHOSPHATE; CALCIUM; NUCLEOPORIN;

ARCHITECTURE; ATOMIC FORCE MICROSCOPY; CELL NUCLEUS; CRYOELECTRON MICROSCOPY; NONHUMAN; NUCLEAR PORE COMPLEX; PRIORITY JOURNAL; REVIEW; YEAST;

EID: 0033151769     PISSN: 09550674     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0955-0674(99)80055-6     Document Type: Review

References (65)

1. Panté N, Aebi U: Molecular dissection of the nuclear pore complex. Crit Rev Biochem Mol Biol 1996, 31:153-199.
2. Fahrenkrog B, Hurt EC, Aebi U, Panté N: Molecular architecture of the yeast nuclear pore complex: Localization of Nsp1p subcomplexes. J Cell Biol 1998, 143:577-588. A new protocol for preparing yeast cells for electron microscopy was developed which yielded structurally well-preserved yeast NPCs. A direct comparison of yeast and Xenopus NPCs revealed that the NPC structure is evolutionarily conserved, although yeast NPCs are 15% smaller in their linear dimensions. With this preparation protocol - and yeast strains expressing nucleoporins tagged with protein A - Nsp1p and its interacting partners Nup49p, Nup57p, Nup82p, and Nic96p were localized by IEM. Accordingly, Nsp1p resides in three distinct subcomplexes that are located at the entry and exit of the central gated channel and at the terminal ring of the nuclear basket.
3. Yang Q, Rout MP, Akey C: Three-dimensional architecture of the isolated yeast nuclear pore complex: Functional and evolutionary implications. Mol Cell 1998, 1:223-234. A three-dimensional map of the yeast NPC from frozen-hydrated specimens was calculated, thereby providing a direct comparison with the vertebrate NPC. Overall, the smaller yeast NPC is comprised of an octagonal inner spoke ring that is anchored within the NE by a novel membrane-interacting ring. In addition, a cylindrical transporter is located centrally within the spokes and exhibits a variable radial expansion in projection that may reflect gating. The inner spoke ring, a transmembrane spoke domain, and the transporter are conserved between yeast and vertebrates; hence, they are required to form a functional NPC. Significant alterations in NPC architecture have arisen during evolution, however, that may be correlated with differences in nuclear transport regulation or mitotic behavior.
4. Goldberg MW, Solovei I, Allen TD: Nuclear pore complex structure in birds. J Struct Biol 1997, 119:284-294.
5. Kiseleva E, Goldberg MW, Allen TD, Akey CW: Active nuclear pore complexes in Chironomous: Visualization of transporter configurations related to mRNP export. J Cell Sci 1998, 111:223-236. The dynamics of NPC structure in salivary gland nuclei from Chironomus during Balbiani ring (BR) particle translocation was investigated by high resolution scanning and transmission electron microscopy revealing evidence of rearrangement of the transporter related to mRNP export. The transporter is an integral part of the NPC and is composed of a central short double cylinder that is retained within the inner spoke ring and two peripheral globular assemblies, which are tethered to the cytoplasmic and nucleoplasmic coaxial rings by eight conserved internal ring filaments. Distinct stages of BR particle nuclear export through the individual NPC components were directly visualized and placed in a linear transport sequence. The BR particle first binds to the NPC basket, which forms an expanded distal basket ring. Furthermore, analysis of the individual NPC components revealed a strong evolutionary conservation of NPC structure between vertebrates and invertebrates.
6. Ris H: High-resolution field-emission scanning electron microscopy of nuclear pore complex. Scanning 1997, 19:368-375.
7. Cordes VK, Reidenbach S, Rackwitz HR, Franke WW: Identification of protein p270/Tpr as a constitutive component of the nuclear pore complex-attached intranuclear filaments. J Cell Biol 1997, 136:515-529.
8. Seedorf M, Damelin M, Kahana J, TAura T, Silver PA: Interactions between a nuclear transporter and a subset of nuclear pore complex proteins depend on Ran GTPase. Mol Cell Biol 1999, 19:1547-1557.
9. Shah S, Tugendreich S, Forbes D: Major binding sites for the nuclear import receptor are the integral nucleoporin Nup153 and the adjacent nuclear filament protein Tpr. J Cell Biol 1998, 141:31-49. Immunoprecipitation experiments revealed that the nucleoporin Nup153 and the pore-associated filament protein Tpr each form stable subcomplexes with importin α and β in Xenopus egg extracts. Nup153 can bind to a complete import complex containing importin α, β, and an NLS substrate, consistent with an involvement of this nucleoporin in a terminal step of nuclear import. Importin β binds directly to Nup153 and can do so at multiple sites in the Nup153 FXFG repeat region in vitro. Tpr, which has no FXFG repeats, binds to importin β and to importin α/β heterodimers, but only to those that do not carry an NLS substrate. The GTP analogue GMP-PNP is able to disassemble importin β complexes with either Nup153 or Tpr. Importantly, analysis of extracts of isolated nuclei indicates that complexes between importin β and Nup153 or Tpr exist in assembled NPCs. Thus, Nup153 and Tpr are major physiological binding sites for importin β.
10. Shah S, Forbes DJ: Separate nuclear import pathways converge on the nucleoporin Nup153 and can be dissected with dominant-negative inhibitors. Curr Biol 1998, 8:1376-1386.
11. Iovine MK, Wente SR: A nuclear export signal in Kap95p is required for both recycling the import factor and the interaction with the nucleoporin GLFG repeat regions of Nup116p and Nup100p. J Cell Biol 1997, 137:797-811.
12. Stochaj U, Méjazi M, Belhumeur P: The small GTPase Gsp1p binds to the repeat domain of the nucleoporin Nsp1p. Biochem J 1998, 330:412-427.
13. Marelli M, Aitchinson JD, Wozniak RW: Specific binding of the karyopherin Kap121p to a subunit of the nuclear pore complex containing Nup53p, Nup59p, and Nup170p. J Cell Biol 1998, 143:1813-1830.
14. Bailer SM, Siniossoglou S, Podtelejnikov A, Hellwig A, Mann M, Hurt E: Nup116p and Nup100p are interchangeable through a conserved motif which constitutes a docking site for the mRNA transport factor Gle2p. EMBO J 1998, 17:1107-1119.
15. Fornerod M, van Deursen J, van Baal S, Reynolds A, Davis D, Murti KG, Fransen J, GRosveld G: The human homologue of yeast CRM1 is in a dynamic subcomplex with CAN/Nup214 and a novel nuclear pore component Nup88. EMBO J 1997, 16:807-816.
16. Yaseen NR, Blobel G: Cloning and characterization of human karyopherin β3. Proc Natl Acad Sci USA 1997, 94:4451-4456.
17. Moroianu J, Blobel G, Radu A: Rangtp-mediated nuclear export of karyopherin α involves its interaction with the nucleoporin Nup153. Proc Natl Acad Sci USA 1997, 94:9899-9704. An interaction between karyopherin α2 and the nucleoporin Nup153 was identified using binding assays and their interacting domains were mapped. An in vitro assay demonstrated that karyopherin α export was stimulated by added GTPase Ran, required GTP hydrolysis, and was inhibited by WGA. RanGTP-mediated export of karyopherin α was inhibited by peptides representing the interacting domains of Nup153 and karyopherin α2; moreover, a cryptic fragment of karyopherin β1, termed β1 *, inhibited import, but not export, of karyopherin α. Hence, karyopherin α import into and export from nuclei are asymmetric processes.
18. Cordes VC, Hase ME, Müller L: Molecular segments of protein Tpr that confer nuclear targeting and association with the nuclear pore complex. Exp Cell Res 1998, 245:43-56. Transaction studies of cultured mammalian cells identified a short region within the carboxy-terminal domain of Trp that is essential and sufficient to mediate nuclear import of Tpr and that can also confer nuclear accumulation of the soluble cytoplasmic protein pyruvate kinase. Tpr deletion mutants that contain this nuclear targeting segment but lack the amino-terminal domain appeared evenly dispersed throughout the nucleus without any noticeable association with the NPC. In contrast, the amino-terminal domain lacking the carboxy-terminal region remained located within the cytoplasm, forming aggregate-like structures not associated with the NE. When tagged with the short nuclear targeting segment of Trp or with the nuclear localization signal of the SV40 large T protein, the amino-terminal domain was imported into the nucleus where it then associated with the NPC.
19. Bangs P, Burke B, Powers C, Craig R, Purohit A, Doxsey S: Functional analysis of Tpr: Identification of nuclear pore complex association and nuclear localization domain and a role in mRNA export. J Cell Biol 1998, 143:1801-1812.
20. Zimowska G, Aris JP, Paddy MR: A Drosophila Tpr protein homolog is localized both in the extrachromosomal channel network and to nuclear pore complexes. J Cell Sci 1997, 110:927-944.
21. Fouchier RAM, Meyer BE, Simon JHM, Fischer U, Albright AV, Gonzalez-Scarrano F, Malim MH: Interaction of the human immundeficiency virus type1 Vpr protein with the nuclear pore complex. J Virol 1998, 72:6004-6013.
22. Zolotukhin A, Felber BK: Nucleoporins Nup98 and Nup214 participate in nuclear export of human immunodeficiency virus type 1 rev. J Virol 1999, 73:120-127.
23. Arai Y, Hosoda F, Kobayashi H, Arai K, Hayashi Y, Nanao K, Kaneko Y, Ohki M: The inv(11)(p15q22) chromosome translocation of de novo and therapy-related myeloid malignancies results in fusion of the nucleoporin gene NUP98, with the putative RNA helicase gene, DDX10. Blood 1997, 89:3936-3944.
24. Raza-Egilmez SZ, Jani-Sait SN, Grossi M, Higgins MJ, Shows TB, Aplan PD: NUP98-HOXD13 gene fusion in therapy-related acute myelogenous leukemia. Cancer Res 1998, 58:4269-4273.
25. Kasper LH, Brindle PK, Schnabel CA, Pritchard CEJ, Cleary ML, van Deursen JMA: CREB binding protein interacts with nucleoporin-specific FG repeats that activate transcription and mediate NUP98-HOAX9 oncogenicity. Mol Cell Biol 1999, 19:764-776.
26. Goldberg MW, Wiese C, Allen TD, Wilson K: Dimples, pores, star rings, and thin rings on growing nuclear envelopes: Evidence for structural intermediates in nuclear pore assembly. J Cell Sci 1997, 110:409-420.
27. Gant TM, Goldberg MW, Allen TD: Nuclear envelope and nuclear pore assembly: Analysis of assembly intermediates by electron microscopy. Curr Opin Cell Biol 1998, 10:409-415.
28. Grandi P, Dang T, Panté N, Shevchenko A, Mann M, Forbes D, Hurt E: Nup93, a vertebrate homologue of yeast Nic96p, forms a complex with a novel 205-kDa protein and is required for correct nuclear pore assembly. Mol Biol Cell 1997, 8:2017-2038. A vertebrate nucleoporin, Nup93, was identified in both human and Xenopus that has proved to be an evolutionarily related homologue of the yeast nucleoporin Nic96p. Immunofluorescence and IEM localized vertebrate Nup93 at the nuclear basket and at or near the nuclear entry to the gated channel of the pore. Immunoprecipitation from both mammalian and Xenopus cell extracts indicated that a small fraction of Nup93 physically interacts with the nucleoporin p62, whereas a large fraction of Nup93 is present in Xenopus egg extracts in complex with a newly discovered 205 kDa protein. The putative human nucleoporin of 205 kDa has related sequence homologues in Caenorhabditis elegans and Saccharomyces cerevisiae. Nuclei depleted in Nup93 complex were clearly defective for correct NPC assembly.
29. Doye V, Hurt E: From nucleoporins to nuclear pore complexes. Curr Opin Cell Biol 1997, 9:401-411.
30. Bucci M, Wente SR: A novel fluorescence-based genetic strategy identifies mutants of Saccharomyces cerevisiae defective for nuclear pore complex assembly. Mol Biol Cell 1998, 9:2439-2461. To identify factors that regulate NPC formation and dynamics, a novel fluorescence-based strategy was used. NPC proteins were tagged with GFP, and the hypothesis that NPC assembly mutants will have distinct GFP-NPC signals compared to wild-type cells was analyzed by fluorescence-activated cell sorting (FACS).
31. Nakielny S, Shaikh S, Burke B, Dreyfuss G: Nup153 is an M9 containing mobile nucleoporin with a novel Ran-binding domain. EMBO J 1999, 18:1982-1995. A phage display system was employed to identify proteins that interact with transportin 1, the import receptor of shuttling hnRNP proteins, with an M9 nuclear localization signal (NLS). Accordingly, Nup153 harbors an M9 NLS and several import and export receptors interact with Nup153 and in a Ran•GTP-regulated fashion. Whereas Ran•GTP dissociates Nup153-import receptor complexes it is required for Nup153-export receptor complexes. Moreover, Nup153 shuttles between the nuclear and cytoplasmic face of the NPC and thus represents a mobile constituent of the NPC that evidently accompanies export cargo toward the cytoplasm.
32. Boer JM, van Deursen JMA, Huib HC, Fransen JAM, Grosveld GC: The nucleoporin CAN/Nup214 binds to both the cytoplasmic and the nucleoplasmic sides of the nuclear pore complex in overexpressing cells. Exp Cell Res 1997, 232:182-185.
33. Bucci M, Wente S: In vivo dynamics of nuclear pore complexes in yeast. J Cell Biol 1997, 136:1185-1199. To investigate the dynamics of NPCs, a live-cell assay in the yeast Saccharomyces cerevisiae was developed. The nucleoporin Nup49p was fused to GFP and expressed in nup49 null haploid yeast cells. When the GFP-Nup49p donor cell was mated with a recipient cell harboring only unlabeled Nup49p, the nuclei fused as a consequence of the normal mating process. By monitoring the distribution of the GFP-Nup49p, fluorescent NPCs were observed to move and encircle the entire nucleus within 25 minutes after fusion. In a mutant strain, where nuclear fusion does not occur, GFP-Nup49p appearance in the recipient nucleus occurred at a very slow rate. GFP-Nup49p labeled NPCs, assembled at 23°C, moved into clusters when the cells were shifted to growth at 37°C, indicating that NPCs can move through the double nuclear membranes and can do so to form NPC clusters in mutant strains.
34. Belgareh N, Doye V: Dynamics of the nuclear pore distribution in nucleoporin mutant yeast cells. J Cell Biol 1997, 136:747-759.
35. Chial HJ, Rout MP, Giddings TH Jr, Winey M: Saccharomyces cerevisiae ndc1p is a shared component of nuclear pore complexes and spindle pole bodies. J Cell Biol 1998, 143:1789-1800. It was demonstrated that Ndc1p is a membrane protein of the NE that localizes to both NPCs and spindle pole bodies (SPBs). Indirect immunofluorescence microscopy revealed that Ndc1p displays punctate, nuclear peripheral localization that colocalizes with a known NPC component, Nup49p, and also with a known SPB component, Spc42p. IEM showed that Ndc1p localizes to the regions of NPCs and SPBs that interact with the NE. A shared function of Ndc1p in the assembly of these organelles into the NE was proposed.
36. +: A gene required for cell cycle-dependent spindle pole body anchoring in the nuclear enevelope and bipolar spindle formation in Schizosaccharomyces pombe. Mol Biol Cell 1998, 9:2839-2855.
37. Yan C, Leibowitz N, Mélèse T: A role for the divergent actin gene, ACT2, in nuclear pore structure and function. EMBO J 1997, 16:3572-3586.
38. Collas P: Nuclear envelope disassembly in mitotic extracts requires functional nuclear pores and a nuclear lamina. J Cell Sci 1998, 111:1293-1303.
39. Feldherr C, Akin D, Moore MS: The nuclear import factor p10 regulates the functional size of the nuclear pore complex during oogenesis. J Cell Sci 1998, 111:1889-1896. Using nucleoplasmin-coated gold as a transport substrate, it was determined that the shift in synthesis from small to large RNAs during oogenesis is accompanied by an increase in both the rates of signal-mediated nuclear import and the functional size of NCPs. It was observed that, nuclear import in oocytes is limited by translocation factors rather than by cytoplasmic binding factors. Analysis of extracts prepared from early and late stage oocytes revealed that the transport factor p10 is more abundant in early stage cells. Indeed, microinjection of purified p10 into later stage oocytes reduced the nuclear import of large gold particles to the level observed in early stage cells. Evidently, p10 can modulate transport through the pores by regulating the functional size of the central transporter element.
40. Rakowska A, Danker T, Schneider SW, Oberleithner H: Atp-induced shape changes of nuclear pores visualized with the atomic force microscope. J Membrane Biol 1998, 163:129-136. The effect of ATP on NPC conformation in isolated NEs from Xenopus laevis oocytes was investigated using AFM. All experiments were conducted in a saline solution mimicking the cytosol. ATP was added during the scanning procedure and the resultant conformational changes of the NPCs were directly monitored, revealing dramatic conformational changes of NPCs subsequent to the addition of ATP. The height of the pores protruding from the cytoplasmic surface of the NE visibly increased whereas the diameter of the pore opening decreased. The observed changes occurred within minutes, were transient and could represent a NPC 'contraction.'
41. Lee MA, Dunn RC, Clapham DE, Stehno-Bittel L: Calcium regulation of nuclear pore permeability. Cell Calcium 1998, 23:91-101.
42. Perez-Terzic C, Jaconi M, Clapham DE: Nuclear calcium and the regulation of the nuclear pore complex. Bioessays 1997, 19:787-792.
43. 2+) of individual nuclear baskets. Most probably, this structural change of the nuclear basket involves its distal ring, which may act as an iris-like diaphragm. To directly correlate distinct structural features with corresponding functional states and dynamic aspects, the putative role of the 'central plug' or 'transporter' was investigated revealing that in the absence of ATP cytoplasmic plugging/unplugging of the NPC is insensitive to calcium.
44. Rutherford SA, Goldberg MW, Allen TD: Three-dimensional visualization of the route of protein import: The role of nuclear pore complex substructures. Exp Cell Res 1997, 232:146-160. The three-dimensional localization of nucleoplasmin and WGA at the NE of Xenopus oocytes was investigated by microinjecting protein coated gold colloids and examining their distribution using both stereo transmission EM and FEISEM. Binding of the WGA gold in the central region of the NPCs appeared to form a barrier, preventing the import of nucleoplasmin gold, and included central localization along radial 'tracks' which correspond to the internal filaments connecting the cytoplasmic ring and the central region of the NPC. It was suggested that these filaments might in some way be involved in opening and closing of the central channel of the NPC for transport. Transport of nucleoplasmin through the central region of the NPCs appeared to be in 'single file' regardless of the size of the colloidal gold, and distribution into the nucleoplasm appeared to be through the basket rings with no association of the nucleoplasmin gold with the basket filaments being observed.
45. Feldherr CM, Akin D: The location of the transport gate in the nuclear pore complex. J Cell Sci 1997, 110:3065-3070.
46. Akey CW, Radermacher M: Architecture of the Xenopus nuclear pore complex revealed by three-dimensional cryo-electron microscopy. J Cell Biol 1993, 122:1-19.
47. Nigg E: Nucleocytoplasmic transport: Signals, mechanisms and regulation. Nature 1997, 386:779-787.
48. Pennisi E: The nucleus's revolving door. Science 1998, 279:1129-1131.
49. Ohno M., Fornerod M, Mattaj IW: Nucleocytoplasmic transport: The last 200 nanometers. Cell 1998, 92:327-336.
50. Hurwitz ME, Strambio-de-Castillia C, Blobel G: Two yeast nuclear pore complex proteins involved in mRNA export of a cytoplasmically oriented subcomplex. Proc Natl Acad Sci USA 1998, 95:11241-11245. The yeast nucleoporin Nup82 was sublocalized to the cytoplasmic side of the NPC by IEM. In vitro binding assays demonstrated that Nup82 interacts with the C-terminal region of Nup159, a yeast nucleoporin that previously was also localized to the cytoplasmic side of the NPC. It was shown that overexpression of Rss1/Gle1 also partially rescued depletion of Nup82, as previously shown for Nup159p. Nup159 and Nup82 might form a cytoplasmically oriented subcomplex of the NPC that is likely associated with Rss1/Gle1, and this complex is essential for RNA export.
51. + RNA export defect in nup82 mutant cells might be due to the loss from the NPCs of Nup159p.
52. Enarson P, Enarson M, Bastos R, Burke B: Amino-terminal sequences that direct nucleoporin Nup153 to the inner surface of the nuclear envelope. Chromosoms 1998, 107:228-236. Nup153 is a large O-linked glycoprotein that is a component of the nuclear basket. The Nup153 molecule has a tripartite structure consisting of N-and C-terminal domains flanking a central zinc finger domain. All of the targeting and assembly information contained within Nup153 is contributed by the N-domain, and can target a cytosolic protein, pyruvate kinase, to the nucleoplasmic face of the NPC. The zinc finger and C-terminal domains appear to have no role in these targeting and assembly activities. Deletion analysis revealed that there are two distinct regions within the Nup153 N-domain that contain different targeting functions. One of these is directly involved in assembly into the NPC while a second overlapping region may target Nup153, as well as other reporter molecules, to the inner face of the NE.
53. Ho Ak, Raczniak GA, Ives EB, Wente SR: The integral membrane protein Snl1p is genetically linked to yeast nuclear pore complex function. Mol Biol Cell 1998, 9:355-373.
54. Watkins JL, Murphy R, Emtage JLT, Wente SR: The human homologue of Saccharomyces cerevisiae Gle1p is required for poly(A)+ RNA export. Proc Natl Acad Sci USA 1998, 95:6779-6784.
55. Yoon JH, Whalen WA, Bharathi A, Shen R, Dhar R: Npp106p, a Schizosaccharomyces pombe nucleoporin similar to Saccharomyces cerevisiae Nic96p, functionally interacts with Rae1p in mRNA export. Mol Cell Biol 1997, 17:7047-7060.
56. Teixeira MT, Siniossoglou S, Podtelejnikov S, Bénichou JC, Mann M, Dujon B, Hurt E, Fabre E: Two functionally distinct domains generated by in vivo cleavage of Nup145p: A novel biogenesis pathway for nucleoporins. EMBO J 1997, 16:5086-5097. Nup145p was cleaved in vivo to yield two functionally distinct domains: a carboxy-terminal domain (C-Nup145p), which is located at the NPC and assembles into the Nup84p complex, and a GLFG-containing amino-terminal domain (N-Nup145p), which is not part of this complex. Whereas the essential C-Nup145p accomplished the functions required for efficient mRNA export and normal NPC distribution, N-Nup145p was not necessary for cell growth, but becomes essential in a nup188 mutant background. Generating a free amino-domain is a prerequisite for complementation of this peculiar synthetic lethal mutant. These data suggested that amino-and carboxyl-domains of Nup145p perform independent functions, and that the in vivo cleavage observed is of functional importance.
57. Dockendorff TC, Heath CV, Goldstein AL, Snay CA, Cole CN: C-terminal truncations of the yeast nucleoporin Nup145p produce a rapid temperature-conditional mRNA export defect and alternations to nuclear structure. Mol Cell Biol 1997, 17:906-920.
58. Emtage JLT, Bucci M, Watkins JL, Wente SR: Defining the essential functional regions of the nucleoporin Nup145p. J Cell Sci 1997, 110:911-925.
59. Del Priore V, Heath CV, Snay CA, Mac Millan A, Gorsch LC, Dagher S, Cole CN: A structure/function analysis of Rat7p/Nup159, an essential nucleoporin of Saccharomyces cerevisiae. J Cell Sci 1997, 110:2987-2999.
60. Hu T, Gerace L: CDNA cloning and analysis of the expression of nucleoporin p45. Gene 1998, 221:245-253.
61. Fischer R, Cordes VC, Franke WW: Sequence analysis of the nuclear pore complex protein in a lower metazoan: Nucleoporin p62 of the coelenterate Hydra vulgaris. Gene 1997, 195:285-293.
62. Bastos R, de Pouplana LR, Enarson M, Bodoor K, Burke B: Nup84, a novel nucleoporin that is associated with CAN/Nup214 on the cytoplasmic face of the nuclear pore complex. J Cell Biol 1997, 137:989-1000. Immunoprecipitation studies revealed a novel nonglycosylated nucleoporin, Nup84, that is tightly associated with CAN/Nup214, and was found to be exposed on the cytoplasmic face of the NPC. Nup84 contains neither the GLFG nor the XFXFG repeats, but secondary structure predictions suggested that Nup84 contains a coiled-coil carboxy-terminal domain. Mutagenesis and expression studies indicated that the putative coiled-coil domain is required for association with the cytoplasmic face of the NPC, whereas the amino-terminal region of Nup84 contains the site of interaction with CAN/Nup214. Nup84 may function in the attachment of CAN/Nup214 to the central framework of the NPC, and could play a central role in the organization of the interface between the pore complex and the cytoplasm.
63. Powers MA, Forbes DJ, Dahlberg JE, Lund E: The vertebrate GLFG nucleoporin, Nup98, is an essential component of multiple RNA export pathways. J Cell Biol 1997, 136:241-250.
64. Söderqvist H, Imreh G, Kihlmark M, Linnmann C, Ringertz N, Hallberg E: Intracellular distribution of an integral nuclear pore membrane protein fused to green fluorescent protein. Eur J Biochem 1997, 250:808-813.
65. Gigliotti S, Callaini G, Andone S, Riparbelli MG, Pernas-Alonso R, Hoffmann G, Grazani F, Malva C: Nup154, a new Drosophila gene essential for male and female gametogenesis is related to the Nup155 vertebrate nucleoporin gene. J Cell Biol 1998, 142:1195-1207.