Snapshot: the Nuclear Envelope I Andrea Rothballer and Ulrike Kutay Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland

Home , Nuclear envelope, Nuclear pore, Nucleoplasm, TOR1AIP1

SnapShot: The Nuclear Envelope I Andrea Rothballer and Ulrike Kutay Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland

The nuclear pore complex The LINC complex

2 P

n a Maimon et al. (2012) R Nup214 GLE1 Nup88 hCG1 Aladin Nup62 Nup160 Nup133 RAE1 Nup107 Nup96 Nup98 Nup85 Nup43 Nup37 Seh1 Sec13 Centrin-2 Nup62 POM121 Nup205 Nup58 Nup188 Nup54 NDC1 Nup155 Nup53 Nup93 Nup45 GP210 Nup53 NDC1 Nup93 Nup45 Sosa et al. (2012) Nup155 Nup188 Nup205 Nup54 POM121 Nup58 TMEM Nup62 33 Sec13 Centrin-2 Nup37 Seh1 SUN KASH Nup85 Nup43 Nup107 Nup96 Nup98 Nup160 Nup 133 RAE1

ELYS Nup153 Nup50

T Linker of Nucleoskeleton and Cytoskeleton P Permeability barrier between nucleoplasm R and cytoplasm Functions in nuclear anchorage and migration, cytoskeletal organization, and chromatin positioning Receptor-mediated translocation of macromolecules FG repeat Nups

Centrosome

Intermediate ﬁlaments Microtubules Kinesin-1 Dynein Plectin Nesprin-2/4 Nesprin-1/2 Actin ER Nesprin-3

Nesprin-1/2 giant

BAF

SUN1/2 Chromatin Lamina

LUMEN

ONM

INM

LEM domain proteins

LUMEN Other nuclear membrane proteins LEM LUMEN LEM-like

MSC LEMD1 Emerin LEMD2 RRM ANK TMEM43 Nurim TMEM201 UNC-50 LAP2β GIY-YIG MAN1 TMEM53 RNase H1 N LBR TOR1AIP1/2

LAP2α LBR Tudor PEMT LAP1C NnrU UNC-50 Ankle2 Connections to lamina and chromatin Ankle1 Functions in signal transduction, gene expression, and chromatin organization

868 Cell 150, August 17, 2012 ©2012 Elsevier Inc. DOI 10.1016/j.cell.2012.07.024 See online version for legend and references. SnapShot: The Nuclear Envelope I Andrea Rothballer and Ulrike Kutay Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland

The Nuclear Envelope The nuclear envelope (NE) separates the nucleoplasm from the cytoplasm in eukaryotic cells, generating the spatial and functional compartmentalization that is essential for the maintenance and processing of genetic information. As a central structural and functional element of the cell, the NE plays key roles in cytoskeletal organization, chromatin positioning, signal transduction, and gene expression. Mutations in various genes of NE proteins cause inherited diseases referred to as nuclear envelopathies, or laminopathies.

Nuclear Pore Complexes Nuclear pore complexes (NPCs) are ~100 MDa protein assemblies with a ring-shaped structure of 8-fold rotational symmetry. The ~30 different protein constituents of NPCs are called nucleoporins (Nups). NPCs form selective passageways between nucleoplasm and cytoplasm. Whereas small molecules diffuse through NPCs freely, macromolecules larger than 30 kDa are restricted in diffusion. Most proteins and RNAs translocate through NPCs by help of shuttling transport receptors that interact with FG-repeat-containing Nups.

Linker of Nucleoskeleton and Cytoskeleton Complexes Linker of nucleoskeleton and cytoskeleton (LINC) complexes establish the physical connection between the nucleus and the cytoskeleton. LINC complexes bridge the NE by association of SUN (Sad1/UNC-84) and KASH (Klarsicht/ANC-1/SYNE homology) domain proteins residing in the inner and outer nuclear membrane (INM and ONM), respec- tively. On the cytoplasmic face of the NE, KASH proteins interact with cytoskeletal components, whereas SUN proteins bind to the nuclear lamina and chromatin in the nuclear interior. Allowing for force transduction, LINC complexes function in processes like nuclear migration and anchorage and meiotic chromosome pairing.

Nuclear Membrane Proteins Most specific nuclear membrane proteins reside in the INM, whereas ONM protein composition largely overlaps with that of the endoplasmic reticulum (ER). INM proteins interact with the nuclear lamina and chromatin and regulate chromatin organization and gene expression. LEM (LAP2/Emerin/MAN1) domain proteins are a well-studied family of INM proteins implicated in chromatin tethering to the nuclear periphery linked to transcriptional silencing. Interaction between the LEM domain and DNA is mediated by the chromatin protein BAF. Proteomic approaches have identified more than 80 novel nuclear membrane proteins, most of which remain to be functionally characterized.

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