Biophysical characterization of interactions involving importin-alpha during nuclear import

Catimel, B., Teh, T., Fontes, M. R. M., Jennings, I. G., Jans, D. A., Howlett, G. J., Nice, E. C. and Kobe, B. (2001) Biophysical characterization of interactions involving importin-alpha during nuclear import. Journal of Biological Chemistry, 276 36: 34189-34198. doi:10.1074/jbc.M103531200

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Author Catimel, B.
Teh, T.
Fontes, M. R. M.
Jennings, I. G.
Jans, D. A.
Howlett, G. J.
Nice, E. C.
Kobe, B.
Title Biophysical characterization of interactions involving importin-alpha during nuclear import
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
Publication date 2001-01-01
Year available 2001
Sub-type Article (original research)
DOI 10.1074/jbc.M103531200
Open Access Status File (Publisher version)
Volume 276
Issue 36
Start page 34189
End page 34198
Total pages 10
Place of publication Maryland
Publisher American Society for Biochemistry & Molecular Biology Inc.
Language eng
Subject C1
270103 Protein Targeting and Signal Transduction
780105 Biological sciences
Abstract Proteins containing the classical nuclear localization sequences (NLSs) are imported into the nucleus by the importin-alpha/beta heterodimer. Importin-alpha contains the NLS binding site, whereas importin-beta mediates the translocation through the nuclear pore. We characterized the interactions involving importin-alpha during nuclear import using a combination of biophysical techniques (biosensor, crystallography, sedimentation equilibrium, electrophoresis, and circular dichroism). Importin-alpha is shown to exist in a monomeric autoinhibited state (association with NLSs undetectable by biosensor). Association with importin-beta (stoichiometry, 1:1; K-D = 1.1 x 10(-8) m) increases the affinity for NLSs; the importin-alpha/beta complex binds representative monopartite NLS (simian virus 40 large T-antigen) and bipartite NLS (nucleoplasmin) with affinities (K-D = 3.5 x 10(-8) m and 4.8 x 10(-8) m, respectively) comparable with those of a truncated importin-alpha lacking the autoinhibitory domain (T-antigen NLS, K-D = 1.7 x 10(-8) m; nucleoplasmin NLS, K-D = 1.4 x 10(-8) m). The autoinhibitory domain (as a separate peptide) binds the truncated importin-alpha, and the crystal structure of the complex resembles the structure of full-length importin-alpha. Our results support the model of regulation of nuclear import mediated by the intrasteric autoregulatory sequence of importin-alpha and provide a quantitative description of the binding and regulatory steps during nuclear import.
Keyword Biochemistry & Molecular Biology
Pore-targeting Complex
T-antigen Nls
Protein Import
Localization Sequence
Crystallographic Analysis
Enhances Recognition
Signal Recognition
Q-Index Code C1
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemistry and Molecular Biosciences
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Citation counts: TR Web of Science Citation Count  Cited 121 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 121 times in Scopus Article | Citations
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Created: Wed, 15 Aug 2007, 01:17:12 EST