scholarly journals Architecture of the Xenopus nuclear pore complex revealed by three-dimensional cryo-electron microscopy

1993 ◽  
Vol 122 (1) ◽  
pp. 1-19 ◽  
Author(s):  
CW Akey ◽  
M Radermacher
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Three Dimensional ◽  
Nucleocytoplasmic Transport ◽  
Domain Model ◽  
Nuclear Pore ◽  
Transport Channel ◽  
Macromolecular Transport ◽  
Cryo Electron Microscopy

The nuclear pore complex spans the nuclear envelope and functions as a macromolecular transporter in the ATP-dependent process of nucleocytoplasmic transport. In this report, we present three dimensional (3D) structures for both membrane-associated and detergent-extracted Xenopus NPCs, imaged in frozen buffers by cryo-electron microscopy. A comparison of the differing configurations present in the 3D maps suggests that the spokes may possess an intrinsic conformational flexibility. When combined with recent data from a 3D map of negatively stained NPCs (Hinshaw, J. E., B. O. Carragher, and R. A. Milligan. 1992. Cell. 69:1133-1141), these observations suggest a minimal domain model for the spoke-ring complex which may account for the observed plasticity of this assembly. Moreover, lumenal domains in adjacent spokes are interconnected by radial arm dimers, forming a lumenal ring that may be responsible for anchoring the NPC within the nuclear envelope pore. Importantly, the NPC transporter is visualized as a centrally tapered cylinder that spans the entire width of the NPC, in a direction normal to the nuclear envelope. The central positioning, tripartite structure, and hollow nature of the transporter suggests that it may form a macromolecular transport channel, with a globular gating domain at each end. Finally, the packing of the transporter within the spokes creates a set of eight internal channels that may be responsible, in part, for the diffusion of ions and small molecules across the nuclear envelope.

scholarly journals Architecture of the fungal nuclear pore inner ring complex

Science ◽  
2015 ◽  
Vol 350 (6256) ◽  
pp. 56-64 ◽  
Author(s):  
Tobias Stuwe ◽  
Christopher J. Bley ◽  
Karsten Thierbach ◽  
Stefan Petrovic ◽  
Sandra Schilbach ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Diffusion Barrier ◽  
Three Dimensional ◽  
Interaction Network ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Transport Channel ◽  
Ring Complex ◽  
And Diffusion

The nuclear pore complex (NPC) constitutes the sole gateway for bidirectional nucleocytoplasmic transport. We present the reconstitution and interdisciplinary analyses of the ~425-kilodalton inner ring complex (IRC), which forms the central transport channel and diffusion barrier of the NPC, revealing its interaction network and equimolar stoichiometry. The Nsp1•Nup49•Nup57 channel nucleoporin heterotrimer (CNT) attaches to the IRC solely through the adaptor nucleoporin Nic96. The CNT•Nic96 structure reveals that Nic96 functions as an assembly sensor that recognizes the three-dimensional architecture of the CNT, thereby mediating the incorporation of a defined CNT state into the NPC. We propose that the IRC adopts a relatively rigid scaffold that recruits the CNT to primarily form the diffusion barrier of the NPC, rather than enabling channel dilation.

scholarly journals Cryo-EM structure of the Inner Ring from Xenopus laevis Nuclear Pore Complex

2021 ◽  
Author(s):  
Gaoxingyu Huang ◽  
Xiechao Zhan ◽  
Chao Zeng ◽  
Ke Liang ◽  
Xuechen Zhu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Xenopus Laevis ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Single Particle ◽  
Nuclear Pore ◽  
Nucleocytoplasmic Shuttling ◽  
Cryo Electron Microscopy

Nuclear pore complex (NPC) mediates nucleocytoplasmic shuttling. Here we present single-particle cryo-electron microscopy (cryo-EM) structure of the inner ring (IR) subunit from Xenopus laevis NPC at an average resolution of 4.4 Å. The symmetric IR subunit comprises a cytoplasmic half and a nuclear half. A homo-dimer of Nup205 resides at the center of the IR subunit, flanked by two molecules of Nup188. Four molecules of Nup93 each places an extended helix into the axial groove of Nup205 or Nup188, together constituting the central scaffold. The channel nucleoporin heterotrimer (CNT) of Nup54/58/62 is anchored on the central scaffold. Six Nup155 molecules interact with the central scaffold and together with the NDC1-ALADIN hetero-dimers anchor the IR subunit to the nuclear envelope and to outer rings. The scarce inter-subunit contacts may allow sufficient latitude in conformation and diameter of the IR. Our structure of vertebrate IR reveals key insights that are functionally important.

scholarly journals Correlation between structure and mass distribution of the nuclear pore complex and of distinct pore complex components.

1990 ◽  
Vol 110 (4) ◽  
pp. 883-894 ◽  
Author(s):  
R Reichelt ◽  
A Holzenburg ◽  
E L Buhle ◽  
M Jarnik ◽  
A Engel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nuclear Envelope ◽  
Three Dimensional ◽  
Structural Features ◽  
Nuclear Pore ◽  
Xenopus Laevis Oocyte ◽  
Three Dimensional Model ◽  
Transmission Electron ◽  
Freeze Dried

Nuclear pore complexes (NPCs) prepared from Xenopus laevis oocyte nuclear envelopes were studied in "intact" form (i.e., unexposed to detergent) and after detergent treatment by a combination of conventional transmission electron microscopy (CTEM) and quantitative scanning transmission electron microscopy (STEM). In correlation-averaged CTEM pictures of negatively stained intact NPCs and of distinct NPC components (i.e., "rings," "spoke" complexes, and "plug-spoke" complexes), several fine structural features arranged with octagonal symmetry about a central axis could reproducibly be identified. STEM micrographs of unstained/freeze-dried intact NPCs as well as of their components yielded comparable but less distinct features. Mass determination by STEM revealed the following molecular masses: intact NPC with plug, 124 +/- 11 MD; intact NPC without plug, 112 +/- 11 MD; heavy ring, 32 +/- 5 MD; light ring, 21 +/- 4 MD; plug-spoke complex, 66 +/- 8 MD; and spoke complex, 52 +/- 3 MD. Based on these combined CTEM and STEM data, a three-dimensional model of the NPC exhibiting eightfold centrosymmetry about an axis perpendicular to the plane of the nuclear envelope but asymmetric along this axis is proposed. This structural polarity of the NPC across the nuclear envelope is in accord with its well-documented functional polarity facilitating mediated nucleocytoplasmic exchange of molecules and particles.

scholarly journals Monoclonal antibodies identify a group of nuclear pore complex glycoproteins.

1987 ◽  
Vol 104 (5) ◽  
pp. 1143-1156 ◽  
Author(s):  
C M Snow ◽  
A Senior ◽  
L Gerace
Keyword(s):  
Monoclonal Antibodies ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Peptide Mapping ◽  
Polyclonal Antibodies ◽  
Integral Membrane Protein ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Surface ◽  
Punctate Pattern

Using monoclonal antibodies we identified a group of eight polypeptides of rat liver nuclear envelopes that have common epitopes. Most or all of these proteins are structurally distinct, as shown by tryptic peptide mapping and analysis with polyclonal antibodies. While these polypeptides are relatively tightly bound to nuclear membranes, only one is an integral membrane protein. The eight antigens cofractionate with the nuclear pore complex under various conditions of ionic strength and detergent. It can be seen by immunofluorescence microscopy that the monoclonal antibodies reacting with these antigens stain the nuclear surface of interphase cells in a finely punctate pattern. When the nuclear envelope is disassembled and subsequently reformed during mitosis, the proteins are reversibly dispersed throughout the cytoplasm in the form of minute foci. By EM immunogold localization on isolated nuclear envelopes, the monoclonal antibodies label exclusively the nuclear pore complex, at both its nucleoplasmic and cytoplasmic margins. Considered together, our biochemical and localization data indicate that the eight nuclear envelope polypeptides are pore complex components. As shown in the accompanying paper (Holt, G. D., C. M. Snow, A. Senior, R. S. Haltiwanger, L. Gerace, and G. W. Hart, J. Cell Biol., 104:1157-1164) these eight polypeptides contain a novel form of glycosylation, O-linked N-acetylglucosamine. The relative abundance and disposition of these O-linked glycoproteins in the pore complex are consistent with their having a role in nucleocytoplasmic transport.

Reticulon-like REEP4 at the inner nuclear membrane promotes nuclear pore complex formation

2021 ◽  
Vol 221 (2) ◽  
Author(s):  
Banafsheh Golchoubian ◽  
Andreas Brunner ◽  
Helena Bragulat-Teixidor ◽  
Annett Neuner ◽  
Busra A. Akarlar ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Inner Nuclear Membrane ◽  
Pore Complexes ◽  
Late Stages ◽  
Protein Complex Assembly

Nuclear pore complexes (NPCs) are channels within the nuclear envelope that mediate nucleocytoplasmic transport. NPCs form within the closed nuclear envelope during interphase or assemble concomitantly with nuclear envelope reformation in late stages of mitosis. Both interphase and mitotic NPC biogenesis require coordination of protein complex assembly and membrane deformation. During early stages of mitotic NPC assembly, a seed for new NPCs is established on chromatin, yet the factors connecting the NPC seed to the membrane of the forming nuclear envelope are unknown. Here, we report that the reticulon homology domain protein REEP4 not only localizes to high-curvature membrane of the cytoplasmic endoplasmic reticulum but is also recruited to the inner nuclear membrane by the NPC biogenesis factor ELYS. This ELYS-recruited pool of REEP4 promotes NPC assembly and appears to be particularly important for NPC formation during mitosis. These findings suggest a role for REEP4 in coordinating nuclear envelope reformation with mitotic NPC biogenesis.

scholarly journals Interactions and structure of the nuclear pore complex revealed by cryo-electron microscopy.

1989 ◽  
Vol 109 (3) ◽  
pp. 955-970 ◽  
Author(s):  
C W Akey
Keyword(s):  
Electron Microscopy ◽  
Mirror Symmetry ◽  
Nuclear Lamina ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Effective Diameter ◽  
Nuclear Pore Complexes ◽  
Cryo Electron Microscopy ◽  
Symmetrical Configuration

Nuclear pore complexes (NPCs) play a central role in mediating nucleocytoplasmic transport and exchange processes in eukaryotic cells. The arrangement and interactions of NPCs within amphibian nuclear envelopes have been studied using cryo-electron microscopy of unfixed and frozen hydrated specimens. The nuclear lamina in Necturus forms an orthogonal network with crossover distances which vary between 1,600 and 4,000 A and which may be related to the basic filament repeat of lamins. Furthermore, the NPCs are attached randomly within the confines of the lamin network, presumably by their nucleoplasmic rings. Image analysis of edge-on and en face projections of detergent-extracted NPCs has been combined with data on the coaxial thin rings to provide a quantitative evaluation of the triple ring model of NPC architecture proposed previously (Unwin, P. N. T., and R. Milligan. 1982. J. Cell Biol. 93:63-75). Additional details of the complex have been visualized including an intimate association of the inner spoke domains as an inner spoke ring, extensive domains within the spokes and coaxial thin rings, and interestingly, a central channel-like feature. Membrane-associated NPCs and detergent-extracted NPCs both possess peripherally located radial arms resulting in an effective diameter of approximately 1,450-1,500 A. In projection, the radial arms possess approximate mirror symmetry suggesting that they originate from both sides of the assembly. Moreover, membrane-associated NPCs are asymmetric at most radii and right-handed as viewed from the cytoplasm; detergent-extracted NPCs appear to be symmetric and have approximately 822 symmetry. Taken together, the data suggests that the framework of membrane-associated NPCs is perturbed from a symmetrical configuration, either during isolation of nuclei or by interactions with the lamina and the nuclear envelope in vivo. However, detergent extraction of nuclei appears to result in a more symmetrical alignment of components in apposing halves of the assembly.

scholarly journals The role of the integral membrane nucleoporins Ndc1p and Pom152p in nuclear pore complex assembly and function

2006 ◽  
Vol 173 (3) ◽  
pp. 361-371 ◽  
Author(s):  
Alexis S. Madrid ◽  
Joel Mancuso ◽  
W. Zacheus Cande ◽  
Karsten Weis
Keyword(s):  
Electron Microscopy ◽  
Saccharomyces Cerevisiae ◽  
Nuclear Envelope ◽  
Lipid Bilayers ◽  
Nuclear Pore Complex ◽  
Transmembrane Proteins ◽  
Nuclear Pore ◽  
Large Channel ◽  
And Function

The nuclear pore complex (NPC) is a large channel that spans the two lipid bilayers of the nuclear envelope and mediates transport events between the cytoplasm and the nucleus. Only a few NPC components are transmembrane proteins, and the role of these proteins in NPC function and assembly remains poorly understood. We investigate the function of the three integral membrane nucleoporins, which are Ndc1p, Pom152p, and Pom34p, in NPC assembly and transport in Saccharomyces cerevisiae. We find that Ndc1p is important for the correct localization of nuclear transport cargoes and of components of the NPC. However, the role of Ndc1p in NPC assembly is partially redundant with Pom152p, as cells lacking both of these proteins show enhanced NPC disruption. Electron microscopy studies reveal that the absence of Ndc1p and Pom152p results in aberrant pores that have enlarged diameters and lack proteinaceous material, leading to an increased diffusion between the cytoplasm and the nucleus.

scholarly journals A large particle associated with the perimeter of the nuclear pore complex.

1982 ◽  
Vol 93 (1) ◽  
pp. 63-75 ◽  
Author(s):  
P N Unwin ◽  
R A Milligan
Keyword(s):  
Electron Microscopy ◽  
Nuclear Pore Complex ◽  
Large Particle ◽  
Xenopus Oocytes ◽  
Three Dimensional ◽  
Central Axis ◽  
Dimensional Structure ◽  
Nuclear Pore ◽  
Three Dimensional Structure ◽  
Large Particles

The three-dimensional structure of the nuclear pore complex has been determined to a resolution of approximately 90 A by electron microscopy using nuclear envelopes from Xenopus oocytes. It is shown to be an assembly of several discrete constituents arranged with octagonal symmetry about a central axis. There are apparent twofold axes perpendicular to the octad axis which suggest that the framework of the pore complex is constructed from two equal but oppositely facing halves. The half facing the cytoplasm is in some instances decorated by large particles, similar in appearance and size to ribosomes.

scholarly journals Nuclear Envelope Regulation of Oncogenic Processes: Roles in Pancreatic Cancer

Epigenomes ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 15 ◽  
Author(s):  
Claudia Preston ◽  
Randolph Faustino
Keyword(s):  
Pancreatic Cancer ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Structural Integrity ◽  
Radiation Treatment ◽  
Tumor Biology ◽  
Nuclear Lamina ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Linc Complex

Pancreatic cancer is an aggressive and intractable malignancy with high mortality. This is due in part to a high resistance to chemotherapeutics and radiation treatment conferred by diverse regulatory mechanisms. Among these, constituents of the nuclear envelope play a significant role in regulating oncogenesis and pancreatic tumor biology, and this review focuses on three specific components and their roles in cancer. The LINC complex is a nuclear envelope component formed by proteins with SUN and KASH domains that interact in the periplasmic space of the nuclear envelope. These interactions functionally and structurally couple the cytoskeleton to chromatin and facilitates gene regulation informed by cytoplasmic activity. Furthermore, cancer cell invasiveness is impacted by LINC complex biology. The nuclear lamina is adjacent to the inner nuclear membrane of the nuclear envelope and can actively regulate chromatin in addition to providing structural integrity to the nucleus. A disrupted lamina can impart biophysical compromise to nuclear structure and function, as well as form dysfunctional micronuclei that may lead to genomic instability and chromothripsis. In close relationship to the nuclear lamina is the nuclear pore complex, a large megadalton structure that spans both outer and inner membranes of the nuclear envelope. The nuclear pore complex mediates bidirectional nucleocytoplasmic transport and is comprised of specialized proteins called nucleoporins that are overexpressed in many cancers and are diagnostic markers for oncogenesis. Furthermore, recent demonstration of gene regulatory functions for discrete nucleoporins independent of their nuclear trafficking function suggests that these proteins may contribute more to malignant phenotypes beyond serving as biomarkers. The nuclear envelope is thus a complex, intricate regulator of cell signaling, with roles in pancreatic tumorigenesis and general oncogenic transformation.

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