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Importin α associates with membranes and participates in nuclear envelope assembly in vitro
Author(s) -
Hachet Virginie,
Köcher Thomas,
Wilm Matthias,
Mattaj Iain W
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600154
Subject(s) - importin , biology , nuclear transport , nls , nuclear localization sequence , microbiology and biotechnology , biochemistry , cell nucleus , nucleus
Importin α is well known as an adaptor that functions with Importin β in the nuclear import of proteins containing specific nuclear localization signals (NLSs). We show here that either an excess or a lack of Importin α blocks nuclear envelope (NE) assembly in vitro , and our data suggest that soluble Importin α functions in NE assembly in conjunction with NLS‐containing partner proteins. Surprisingly, a significant proportion of Importin α is found to fractionate with Xenopus egg membranes. We demonstrate that membrane association of Importin α is regulated by phosphorylation. Using mutant forms of Importin α that either do not bind membranes or are not released from them by phosphorylation, we provide evidence that membrane‐associated Importin α is required for NE formation. Unlike other functions of Importin α, this membrane‐associated activity does not require interaction with NLS proteins.