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Encyclopedia > Nuclear Localization Signal

A nuclear localizing sequence (NLS) is an amino acid sequence which acts like a 'tag' on the exposed surface of a protein. This sequence is used to confine the protein to the cell nucleus through the Nuclear Pore Complex and to direct a newly synthesized protein into the nucleus via its recognition by cytosolic nuclear transport receptors. Typically, this signal consists of a few short sequences of positively charged lysines or arginines. Different nuclear localized proteins may share the same NLS. Phenylalanine is one of the standard amino acids. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Nuclear pore. ...


Genetically the NLS results from transcription of a nuclear localizing sequence. Cellular processes and protein function may be studied by adding a known NLS sequence to a gene, confining the chimeric protein product to the nucleus. A NLS has the opposite function of a nuclear export signal, which confines proteins to the cytosolic face of the nuclear membrane. Typically the NLS will have a sequence (NH2)-Pro-Pro-Lys-Lys-Lys-Arg-Lys-Val-(COOH). A Chimera (or chimeric protein) is a human-engineered protein that is encoded by a nucleotide sequence made by a splicing together of two or more complete or partial genes. ... The eukaryotic cell nucleus. ... It has been suggested that this article or section be merged into Protein targeting. ... The cytosol (as opposed to cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ... The nuclear envelope refers to the double membrane of the nucleus that encloses genetic material in eukaryotic cells. ...


A protein translated with a NLS will bind strongly to importin, and together, the complex will move through the nuclear pore. At this point, Ran-GTP will bind to the importin-protein complex, and its binding will cause the importin to lose affinity for the protein. The protein is released, and now the Ran-GTP/importin complex will move back out of the nucleus through the nuclear pore. A GTPase activating protein (GAP) in the cytoplasm hydrolyzes the Ran-GTP to GDP, and this causes a conformational change in Ran, ultimately reducing its affinity for importin. Importin is released and Ran-GDP is recycled back to the nucleus where guanine exchange factor (GEF) exchanges its GDP back for GTP. Karyopherins are a group of proteins involved in transporting molecules through the nuclear pores of the nuclear envelope. ... GTPase Activating Protein, or GAP, is one of a group of biochemical compounds responsible for the activation of the GTPase function of GTP-binding proteins. ...


Proteins gain entry into the nucleus through the nuclear envelope. The nuclear envelope consist of concentric membranes, the outer and the inner membrane. These are the gateways to the nucleus. The envelope consist of pores or large nuclear complexes.


References


Gorlich, D. (1997). Nuclear protein import. Current Opinion in Cell Biology, 9(3), 412-419.


  Results from FactBites:
 
A Ty1 integrase nuclear localization signal required for retrotransposition. (217 words)
The transposition components are assembled in the cytoplasm and must cross the nuclear envelope to reach the genomic target since the yeast cell nuclear membrane remains intact throughout the cell cycle.
We have identified a bipartite nuclear localization signal (NLS) in IN that directs IN to the nucleus and is required for Ty1 transposition.
Mutations in the NLS that specifically abolish nuclear localization inactivate transpositional integration but do not affect reverse transcription, protein processing, or catalytic activity in vitro.
The nuclear localization signal of a pollen-specific, desiccation-associated protein of lily is necessary and ... (3477 words)
The nuclear localization signal of a pollen-specific, desiccation-associated protein of lily is necessary and sufficient for nuclear targeting
To investigate the nuclear targeting property of NLS in LLA23, a green fluorescent protein (GFP) gene fused with the C-terminal half of LLA23 (GFP-LLA23) was constructed.
Fluorescence microscopic studies indicated that the NLS in LLA23 exhibited a property of nuclear localization signals, showing highly condensed spots of green fluorescence in leaf cells (Figure 3B), whereas GFP alone was apparently distributed in the cytoplasm of whole leaf cells (Figure 3A).
  More results at FactBites »


 

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