scholarly journals Ran-binding protein 5 (RanBP5) is related to the nuclear transport factor importin-beta but interacts differently with RanBP1.

1997 ◽  
Vol 17 (9) ◽  
pp. 5087-5096 ◽  
Author(s):  
R Deane ◽  
W Schäfer ◽  
H P Zimmermann ◽  
L Mueller ◽  
D Görlich ◽  
...  
Keyword(s):  
Nuclear Transport ◽  
Binding Protein ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nucleotide Exchange ◽  
Transport Pathway ◽  
Importin Beta ◽  
Pore Complexes

We report the identification and characterization of a novel 124-kDa Ran binding protein, RanBP5. This protein is related to importin-beta, the key mediator of nuclear localization signal (NLS)-dependent nuclear transport. RanBP5 was identified by two independent methods: it was isolated from HeLa cells by using its interaction with RanGTP in an overlay assay to monitor enrichment, and it was also found by the yeast two-hybrid selection method with RanBP1 as bait. RanBP5 binds to RanBP1 as part of a trimeric RanBP1-Ran-RanBP5 complex. Like importin-beta, RanBP5 strongly binds the GTP-bound form of Ran, stabilizing it against both intrinsic and RanGAP1-induced GTP hydrolysis and also against nucleotide exchange. The GAP resistance of the RanBP5-RanGTP complex can be relieved by RanBP1, which might reflect an in vivo role for RanBP1. RanBP5 is a predominantly cytoplasmic protein that can bind to nuclear pore complexes. We propose that RanBP5 is a mediator of a nucleocytoplasmic transport pathway that is distinct from the importin-alpha-dependent import of proteins with a classical NLS.

scholarly journals O-GlcNAc modification of nuclear pore complexes accelerates bi-directional transport

2020 ◽  
Author(s):  
Tae Yeon Yoo ◽  
Timothy J Mitchison
Keyword(s):  
Nuclear Import ◽  
Nuclear Transport ◽  
Super Resolution ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Permeability Barrier ◽  
Nuclear Pore Complexes ◽  
Facilitated Diffusion ◽  
Import And Export ◽  
Pore Complexes

AbstractMacromolecular transport across the nuclear envelope depends on facilitated diffusion through nuclear pore complexes (NPCs). The interior of NPCs contains a permeability barrier made of phenylalanine-glycine (FG) repeat domains that selectively facilitates the permeation of cargoes bound to nuclear transport receptors (NTRs). FG repeats in NPC are a major site of O-linked N-acetylglucosamine (O-GlcNAc) modification, but the functional role of this modification in nucleocytoplasmic transport is unclear. We developed high-throughput assays based on optogenetic probes to quantify the kinetics of nuclear import and export in living human cells. We found that increasing O-GlcNAc modification of the NPC accelerated NTR-facilitated nucleocytoplasmic transport of proteins in both directions, and decreasing modification slowed transport. Super-resolution imaging revealed strong enrichment of O-GlcNAc at the FG-repeat barrier. O-GlcNAc modification also accelerated passive permeation of a small, inert protein through NPCs. We conclude that O-GlcNAc modification accelerates nucleocytoplasmic transport by enhancing the non-specific permeability the FG-repeat barrier, perhaps by steric inhibition of interactions between FG repeats.SummaryNuclear pore complexes mediate nuclear transport and are highly modified with O-linked N-acetylglucosamine (O-GlcNAc) on FG repeat domains. Using a new quantitative live-cell imaging assay, Yoo and Mitchison demonstrate acceleration of nuclear import and export by O-GlcNAc modification.

scholarly journals The FG-repeat asymmetry of the nuclear pore complex is dispensable for bulk nucleocytoplasmic transport in vivo

2004 ◽  
Vol 167 (4) ◽  
pp. 583-590 ◽  
Author(s):  
Bryan Zeitler ◽  
Karsten Weis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Pore Complex ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nucleocytoplasmic Trafficking ◽  
Transport Pathways ◽  
Pore Complexes ◽  
Biased Distribution

Nucleocytoplasmic transport occurs through gigantic proteinaceous channels called nuclear pore complexes (NPCs). Translocation through the NPC is exquisitely selective and is mediated by interactions between soluble transport carriers and insoluble NPC proteins that contain phenylalanine-glycine (FG) repeats. Although most FG nucleoporins (Nups) are organized symmetrically about the planar axis of the nuclear envelope, very few localize exclusively to one side of the NPC. We constructed Saccharomyces cerevisiae mutants with asymmetric FG repeats either deleted or swapped to generate NPCs with inverted FG asymmetry. The mutant Nups localize properly within the NPC and exhibit exchanged binding specificity for the export factor Xpo1. Surprisingly, we were unable to detect any defects in the Kap95, Kap121, Xpo1, or mRNA transport pathways in cells expressing the mutant FG Nups. These findings suggest that the biased distribution of FG repeats is not required for major nucleocytoplasmic trafficking events across the NPC.

scholarly journals Leukemia-Associated Nup214 Fusion Proteins Disturb the XPO1-Mediated Nuclear-Cytoplasmic Transport Pathway and Thereby the NF-κB Signaling Pathway

2016 ◽  
Vol 36 (13) ◽  
pp. 1820-1835 ◽  
Author(s):  
Shoko Saito ◽  
Sadik Cigdem ◽  
Mitsuru Okuwaki ◽  
Kyosuke Nagata
Keyword(s):  
Signaling Pathway ◽  
Nuclear Export ◽  
Fusion Proteins ◽  
Nuclear Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Transport Pathway ◽  
Cytoplasmic Transport ◽  
Transport Receptors ◽  
Pore Complexes

Nuclear-cytoplasmic transport through nuclear pore complexes is mediated by nuclear transport receptors. Previous reports have suggested that aberrant nuclear-cytoplasmic transport due to mutations or overexpression of nuclear pore complexes and nuclear transport receptors is closely linked to diseases. Nup214, a component of nuclear pore complexes, has been found as chimeric fusion proteins in leukemia. Among various Nup214 fusion proteins, SET-Nup214 and DEK-Nup214 have been shown to be engaged in tumorigenesis, but their oncogenic mechanisms remain unclear. In this study, we examined the functions of the Nup214 fusion proteins by focusing on their effects on nuclear-cytoplasmic transport. We found that SET-Nup214 and DEK-Nup214 interact with exportin-1 (XPO1)/CRM1 and nuclear RNA export factor 1 (NXF1)/TAP, which mediate leucine-rich nuclear export signal (NES)-dependent protein export and mRNA export, respectively. SET-Nup214 and DEK-Nup214 decreased the XPO1-mediated nuclear export of NES proteins such as cyclin B and proteins involved in the NF-κB signaling pathway by tethering XPO1 onto nuclear dots where Nup214 fusion proteins are localized. We also demonstrated that SET-Nup214 and DEK-Nup214 expression inhibited NF-κB-mediated transcription by abnormal tethering of the complex containing p65 and its inhibitor, IκB, in the nucleus. These results suggest that SET-Nup214 and DEK-Nup214 perturb the regulation of gene expression through alteration of the nuclear-cytoplasmic transport system.

scholarly journals Scaffold nucleoporins Nup188 and Nup192 share structural and functional properties with nuclear transport receptors

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Kasper R Andersen ◽  
Evgeny Onischenko ◽  
Jeffrey H Tang ◽  
Pravin Kumar ◽  
James Z Chen ◽  
...  
Keyword(s):  
Nuclear Transport ◽  
Evolutionary Relationship ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Rotational Axis ◽  
Nuclear Pore Complexes ◽  
Facilitated Diffusion ◽  
Structural And Functional Properties ◽  
Transport Receptors ◽  
Pore Complexes

Nucleocytoplasmic transport is mediated by nuclear pore complexes (NPCs) embedded in the nuclear envelope. About 30 different proteins (nucleoporins, nups) arrange around a central eightfold rotational axis to build the modular NPC. Nup188 and Nup192 are related and evolutionary conserved, large nucleoporins that are part of the NPC scaffold. Here we determine the structure of Nup188. The protein folds into an extended stack of helices where an N-terminal 130 kDa segment forms an intricate closed ring, while the C-terminal region is a more regular, superhelical structure. Overall, the structure has distant similarity with flexible S-shaped nuclear transport receptors (NTRs). Intriguingly, like NTRs, both Nup188 and Nup192 specifically bind FG-repeats and are able to translocate through NPCs by facilitated diffusion. This blurs the existing dogma of a clear distinction between stationary nups and soluble NTRs and suggests an evolutionary relationship between the NPC and the soluble nuclear transport machinery.

Nucleocytoplasmic transport of macromolecules

1997 ◽  
Vol 61 (2) ◽  
pp. 193-211
Author(s):  
A H Corbett ◽  
P A Silver
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Transport ◽  
Bound State ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Yeast Saccharomyces Cerevisiae ◽  
Soluble Factors ◽  
Pore Complexes ◽  
Transport Of Macromolecules

Nucleocytoplasmic transport is a complex process that consists of the movement of numerous macromolecules back and forth across the nuclear envelope. All macromolecules that move in and out of the nucleus do so via nuclear pore complexes that form large proteinaceous channels in the nuclear envelope. In addition to nuclear pores, nuclear transport of macromolecules requires a number of soluble factors that are found both in the cytoplasm and in the nucleus. A combination of biochemical, genetic, and cell biological approaches have been used to identify and characterize the various components of the nuclear transport machinery. Recent studies have shown that both import to and export from the nucleus are mediated by signals found within the transport substrates. Several studies have demonstrated that these signals are recognized by soluble factors that target these substrates to the nuclear pore. Once substrates have been directed to the pore, most transport events depend on a cycle of GTP hydrolysis mediated by the small Ras-like GTPase, Ran, as well as other proteins that regulate the guanine nucleotide-bound state of Ran. Many of the essential factors have been identified, and the challenge that remains is to determine the exact mechanism by which transport occurs. This review attempts to present an integrated view of our current understanding of nuclear transport while highlighting the contributions that have been made through studies with genetic organisms such as the budding yeast, Saccharomyces cerevisiae.

scholarly journals RanGAP1*SUMO1 is phosphorylated at the onset of mitosis and remains associated with RanBP2 upon NPC disassembly

2004 ◽  
Vol 164 (7) ◽  
pp. 965-971 ◽  
Author(s):  
Sowmya Swaminathan ◽  
Florian Kiendl ◽  
Roman Körner ◽  
Raffaella Lupetti ◽  
Ludger Hengst ◽  
...  
Keyword(s):  
Cyclin B1 ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Accumulation ◽  
Stable Complex ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
M Phase ◽  
Pore Complexes

The RanGTPase activating protein RanGAP1 has essential functions in both nucleocytoplasmic transport and mitosis. In interphase, a significant fraction of vertebrate SUMO1-modified RanGAP1 forms a stable complex with the nucleoporin RanBP2/Nup358 at nuclear pore complexes. RanBP2 not only acts in the RanGTPase cycle but also is a SUMO1 E3 ligase. Here, we show that RanGAP1 is phosphorylated on residues T409, S428, and S442. Phosphorylation occurs before nuclear envelope breakdown and is maintained throughout mitosis. Nocodazole arrest leads to quantitative phosphorylation. The M-phase kinase cyclin B/Cdk1 phosphorylates RanGAP1 efficiently in vitro, and T409 phosphorylation correlates with nuclear accumulation of cyclin B1 in vivo. We find that phosphorylated RanGAP1 remains associated with RanBP2/Nup358 and the SUMO E2–conjugating enzyme Ubc9 in mitosis, hence mitotic phosphorylation may have functional consequences for the RanGTPase cycle and/or for RanBP2-dependent sumoylation.

scholarly journals Molecular basis for Nup37 and ELY5/ELYS recruitment to the nuclear pore complex

2012 ◽  
Vol 109 (38) ◽  
pp. 15241-15246 ◽  
Author(s):  
Silvija Bilokapic ◽  
Thomas U. Schwartz
Keyword(s):  
Nucleocytoplasmic Transport ◽  
Biological Data ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Multiple Copies ◽  
Critical Unit ◽  
Species Specific ◽  
Pore Complexes

Nucleocytoplasmic transport is mediated by nuclear pore complexes (NPCs), enormous assemblies composed of multiple copies of ∼30 different proteins called nucleoporins. To unravel the basic scaffold underlying the NPC, we have characterized the species-specific scaffold nucleoporin Nup37 and ELY5/ELYS. Both proteins integrate directly via Nup120/160 into the universally conserved heptameric Y-complex, the critical unit for the assembly and functionality of the NPC. We present the crystal structure of Schizosaccharomyces pombe Nup37 in complex with Nup120, a 174-kDa subassembly that forms one of the two short arms of the Y-complex. Nup37 binds near the bend of the L-shaped Nup120 protein, potentially stabilizing the relative orientation of its two domains. By means of reconstitution assays, we pinpoint residues crucial for this interaction. In vivo and in vitro results show that ELY5 binds near an interface of the Nup120–Nup37 complex. Complementary biochemical and cell biological data refine and consolidate the interactions of Nup120 within the current Y-model. Finally, we propose an orientation of the Y-complex relative to the pore membrane, consistent with the lattice model.

scholarly journals In Vivo Dynamics of Nuclear Pore Complexes in Yeast

1997 ◽  
Vol 136 (6) ◽  
pp. 1185-1199 ◽  
Author(s):  
Mirella Bucci ◽  
Susan R. Wente
Keyword(s):  
Nuclear Envelope ◽  
Recipient Cell ◽  
Nucleocytoplasmic Transport ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Central Location ◽  
Nuclear Membranes ◽  
Mutant Strains ◽  
Pore Complexes

While much is known about the role of nuclear pore complexes (NPCs) in nucleocytoplasmic transport, the mechanism of NPC assembly into pores formed through the double lipid bilayer of the nuclear envelope is not well defined. To investigate the dynamics of NPCs, we developed a live-cell assay in the yeast Saccharomyces cerevisiae. The nucleoporin Nup49p was fused to the green fluorescent protein (GFP) of Aequorea victoria 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, we could assess whether NPCs were able to move from the donor section of the nuclear envelope to that of the recipient nucleus. We observed that fluorescent NPCs moved and encircled the entire nucleus within 25 min after fusion. When assays were done in mutant kar1-1 strains, where nuclear fusion does not occur, GFP–Nup49p appearance in the recipient nucleus occurred at a very slow rate, presumably due to new NPC biogenesis or to exchange of GFP– Nup49p into existing recipient NPCs. Interestingly, in a number of existing mutant strains, NPCs are clustered together at permissive growth temperatures. This has been explained with two different hypotheses: by movement of NPCs through the double nuclear membranes with subsequent clustering at a central location; or, alternatively, by assembly of all NPCs at a central location (such as the spindle pole body) with NPCs in mutant cells unable to move away from this point. Using the GFP–Nup49p system with a mutant in the NPCassociated factor Gle2p that exhibits formation of NPC clusters only at 37°C, it was possible to distinguish between these two models for NPC dynamics. GFP– Nup49p-labeled NPCs, assembled at 23°C, moved into clusters when the cells were shifted to growth at 37°C. These results indicate that NPCs can move through the double nuclear membranes and, moreover, can do so to form NPC clusters in mutant strains. Such clusters may result by releasing NPCs from a nuclear tether, or by disappearance of a protein that normally prevents pore aggregation. This system represents a novel approach for identifying regulators of NPC assembly and movement in the future.

Recombinant Nup153 Incorporates in Vivo into Xenopus Oocyte Nuclear Pore Complexes

2000 ◽  
Vol 129 (2-3) ◽  
pp. 306-312 ◽  
Author(s):  
Nelly Panté ◽  
Franziska Thomas ◽  
Ueli Aebi ◽  
Brian Burke ◽  
Ricardo Bastos
Keyword(s):  
Xenopus Oocyte ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Pore Complexes

scholarly journals Nuclear Pore Proteins in Regulation of Chromatin State

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1414 ◽  
Author(s):  
Terra M. Kuhn ◽  
Maya Capelson
Keyword(s):  
Nucleosome Occupancy ◽  
Regulation Of Gene Expression ◽  
Nucleocytoplasmic Transport ◽  
Chromatin State ◽  
Nuclear Pore ◽  
Regulation Of Transcription ◽  
Nuclear Pore Complexes ◽  
Functional Connection ◽  
Histone Modifiers ◽  
Pore Complexes

Nuclear pore complexes (NPCs) are canonically known to regulate nucleocytoplasmic transport. However, research efforts over the last decade have demonstrated that NPCs and their constituent nucleoporins (Nups) also interact with the genome and perform important roles in regulation of gene expression. It has become increasingly clear that many Nups execute these roles specifically through regulation of chromatin state, whether through interactions with histone modifiers and downstream changes in post-translational histone modifications, or through relationships with chromatin-remodeling proteins that can result in physical changes in nucleosome occupancy and chromatin compaction. This review focuses on these findings, highlighting the functional connection between NPCs/Nups and regulation of chromatin structure, and how this connection can manifest in regulation of transcription.

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