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PMID: 8617226 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

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

The EMBO journal ·Vol. 15 ·No. 8 ·1996-04-15 ·Pages 1810-7

Görlich D, Henklein P, Laskey RA, 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.

MeSH Terms
Amino Acid Sequence Animals Binding Sites/genetics Biological Transport, Active Cell Nucleus/metabolism Consensus Sequence Cytoplasm/metabolism DNA, Complementary/genetics Evolution, Molecular Female Humans In Vitro Techniques Karyopherins Molecular Sequence Data Molecular Structure Nuclear Envelope/metabolism Nuclear Proteins/chemistry,genetics,metabolism Oocytes/metabolism Protein Binding Recombinant Proteins/chemistry,genetics,metabolism Xenopus
Chemicals
DNA, Complementary Karyopherins Nuclear Proteins Recombinant Proteins
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Görlich D
Wellcome/CRC Institute, Cambridge, UK
Henklein P
Laskey R A
Hartmann E
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33 references, click to expand
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Article Info
Journal
The EMBO journal
Abbr.
EMBO J
ISSN
0261-4189
Published
1996-04-15
Pages
1810-7
Language
English
Region
England
NLM ID
8208664
PMCID
PMC450097
Subset
IM
Grants
Wellcome Trust · United Kingdom
External Links
PubMed source PMC Full Text View journal details
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