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Heterokaryon Technique for Analysis of Cell Type-specific Localization
Published on: March 11, 2011
Nuclear localization properties of a conserved protuberance in the Sm core complex
Cyrille Girard1, John Mouaikel, Henry Neel
1Institut de Génétique Moléculaire, IFR122, CNRS UMR 5535, Montpellier, France.
Experimental Cell Research
|August 11, 2004
Summary
The nuclear import of small nuclear ribonucleoproteins (snRNPs) involves a cap structure and Sm core nuclear localization signal (NLS). Human SmD1 and SmD3 C-terminal domains mediate this NLS, suggesting evolutionary conservation.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Nuclear import of small nuclear ribonucleoproteins (snRNPs) is crucial for gene expression regulation.
- The snRNP import signal comprises the m(3)G cap and the Sm core nuclear localization signal (NLS).
- The precise composition of the Sm core NLS in mammals remains undefined.
Purpose of the Study:
- To identify the specific protein domains responsible for the Sm core NLS in human snRNPs.
- To investigate the evolutionary conservation of the Sm core NLS.
Main Methods:
- Green fluorescent protein (GFP) fusion constructs of human Sm proteins were utilized.
- Immunolocalization and biochemical experiments were performed.
- Deletion mutants of Sm protein C-terminal domains were analyzed.
Main Results:
- The C-terminal domains of human SmD1 and SmD3 proteins were shown to possess nuclear localization properties.
- Deletion of these C-terminal domains resulted in increased cytoplasmic localization of GFP-Sm fusion proteins.
- These findings support a model of evolutionary conserved Sm core NLS.
Conclusions:
- The C-terminal domains of human SmD1 and SmD3 are key components of the Sm core NLS.
- The Sm core NLS is likely composed of a basic-rich protuberance formed by C-terminal domains of various Sm subtypes.
- This mechanism for nuclear import of snRNPs is evolutionarily conserved across species.
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