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A 41 amino acid motif in importin-alpha confers binding to importin-beta and hence transit into the nucleus

Item Type:Article
Title:A 41 amino acid motif in importin-alpha confers binding to importin-beta and hence transit into the nucleus
Creators Name:Goerlich, D. and Henklein, P. and Laskey, R.A. and Hartmann, E.
Abstract:The complex of importin-alpha and -beta is essential for nuclear protein import. It binds the import substrate in the cytosol, and the resulting trimeric complex moves through the nuclear pores, probably as a single entity. Importin-alpha provides the nuclear localization signal binding site, importin-beta the site of initial docking to the pore. Here we show that the conserved, basic N-terminus of importin-alpha is sufficient for importin-beta binding and essential for protein import. The fusion product of this 41 amino acid domain to a heterologous protein if transported into the nucleus in the same way as full-length importin-alpha itself. Transport is dependent on importin-beta but competed by importin-alpha. As no additional part of importin-alpha is needed for translocation, the movement which drives the import substrate complex into the nucleus appears to be generated between importin-beta and structures of the nuclear pore. The domain that binds to importin-beta appears to confer import only, but not re-export out of the nucleus, suggesting that the return of importin-alpha into the cytoplasm is not a simple reversal of its entry.
Keywords:IBB Domain, Importin, Nuclear Pore, Nuclear Transport, Ran, Animals, Xenopus
Source:EMBO Journal
ISSN:0261-4189
Publisher:Nature Publishing Group
Volume:15
Number:8
Page Range:1810-1817
Date:15 April 1996
Official Publication:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC450097/?tool=pubmed
PubMed:View item in PubMed

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