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Nuclear import factors importin alpha and importin beta undergo mutually induced conformational changes upon
G Cingolani1, H A Lashuel, L Gerace
1Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
FEBS Letters
|November 18, 2000
Summary
Nuclear import involves importin alpha and importin beta. Their interaction, mediated by importin alpha's IBB domain, induces conformational changes in both proteins, facilitating nuclear transport.
Area of Science:
- Molecular Biology
- Cell Biology
- Structural Biology
Background:
- Nuclear import of proteins relies on importin alpha and importin beta forming a heterodimer.
- The importin beta:importin alpha interaction is crucial and mediated by the IBB domain of importin alpha.
Purpose of the Study:
- To investigate the conformational changes during the formation of the importin beta:IBB domain complex in solution.
- To elucidate the molecular mechanisms underlying nuclear import of proteins with nuclear localization signals (NLS).
Main Methods:
- Biochemical techniques
- Biophysical techniques
- X-ray crystallography (for prior structural data)
Main Results:
- Importin beta adopts a compact, proteolytically resistant conformation upon binding the IBB domain.
- The IBB domain folds into an alpha helix when interacting with importin beta.
- These findings suggest mutually induced conformational changes drive complex formation.
Conclusions:
- A model is proposed for how dual conformational changes orchestrate NLS cargo nuclear import.
- Understanding these dynamics is key to comprehending nuclear transport regulation.