Related Experiment Video
Updated: Jul 7, 2026
12:13
Single-Molecule Imaging of Nuclear Transport
Published on: June 9, 2010
The Nup358-RanGAP complex is required for efficient importin alpha/beta-dependent nuclear import
Saskia Hutten1, Annette Flotho, Frauke Melchior
1Department of Biochemistry I, Faculty of Medicine, Georg-August University of Göttingen, 37073, Göttingen, Germany.
Molecular Biology of the Cell
|February 29, 2008
Summary
The nucleoporin Nup358-RanGAP1 complex is crucial for nuclear protein transport, regulating importin beta recycling and import complex formation. Its depletion impairs nuclear import, highlighting its dual role in nucleocytoplasmic transport pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The nucleoporin Nup358/RanBP2 is a key component of the nuclear pore complex, interacting with SUMOylated RanGAP1.
- RanGAP1 is essential for establishing the RanGTP gradient critical for nucleocytoplasmic transport.
Purpose of the Study:
- To investigate the roles of the Nup358-RanGAP1 complex and soluble RanGAP1 in nuclear protein transport.
- To elucidate the mechanisms by which Nup358 influences nucleocytoplasmic transport.
Main Methods:
- RNA interference to deplete Nup358 in vertebrate cells.
- In vivo and in vitro reconstitution assays.
- Antibody-inhibition experiments targeting RanGAP1.
Main Results:
- Nup358 depletion significantly reduced importin alpha/beta-dependent nuclear import.
- Overexpression of importin beta rescued nuclear import in Nup358-depleted cells, indicating it's rate-limiting.
- Antibodies against RanGAP1 inhibited nuclear import and export, with partial rescue of import by soluble RanGAP.
Conclusions:
- The Nup358-RanGAP1 complex has a dual function in coordinating importin beta recycling and the reformation of new import complexes.
- Nup358 is essential for efficient nucleocytoplasmic transport, particularly for nuclear import.
- RanGAP1 activity is critical for both nuclear import and export processes.
Related Concept Videos
01:46Nuclear Localization Signals and Import
Proteins targeted to the nucleus carry short stretches of amino acid sequences called the nuclear localization signal or NLS. Classical nuclear localization signals are of two types: monopartite and bipartite NLS. Monopartite classical NLS (cNLS) consists of a single cluster of 4-8 amino acids. Bipartite cNLS consists of two clusters of 2-3 amino acids and a 9-12 residue long proline-rich linker bridging the two clusters. Signal clusters are rich in positively charged amino acids such as...
01:34Nuclear Protein Sorting
Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
01:42Nuclear Export
The nucleus restricts several proteins within and allows others to pass. The restricted proteins possess a nuclear retention sequence or NRS, anchoring them to the nuclear lamins and preventing their transport to the cytosol. The non-restricted proteins, after their synthesis, are transported to their site of action, such as the cytosol or other organelles, with the help of nuclear export signals or NES.
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
01:42Directionality of Nuclear Transport
Ras-related nuclear protein or Ran is a small G protein that cycles between its GTP and GDP bound states. Ran specific regulators, a Ran GTPase Activating Protein or RanGAP present in the cytosol and a Ran guanine nucleotide exchange factor or RanGEF present inside the nucleus regulate GTP/GDP exchange. A high concentration of GTP inside the cells, in addition to this asymmetric distribution of Ran-specific regulators, leads to a higher RanGTP concentration inside the nucleus. This...
02:31Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
02:31Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...