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Importin alpha is well known as an adaptor that functions with Importin beta in the nuclear import of proteins containing specific nuclear localization signals (NLSs). We show here that either an excess or a lack of Importin alpha blocks nuclear envelope (NE) assembly in vitro, and our data suggest that soluble Importin alpha functions in NE assembly in conjunction with NLS-containing partner proteins. Surprisingly, a significant proportion of Importin alpha is found to fractionate with Xenopus egg membranes. We demonstrate that membrane association of Importin alpha is regulated by phosphorylation. Using mutant forms of Importin alpha that either do not bind membranes or are not released from them by phosphorylation, we provide evidence that membrane-associated Importin alpha is required for NE formation. Unlike other functions of Importin alpha, this membrane-associated activity does not require interaction with NLS proteins.
Askjaer,
Ran GTPase cycle and importins alpha and beta are essential for spindle formation and nuclear envelope assembly in living Caenorhabditis elegans embryos.
2002, Pubmed
Askjaer,
Ran GTPase cycle and importins alpha and beta are essential for spindle formation and nuclear envelope assembly in living Caenorhabditis elegans embryos.
2002,
Pubmed Azuma,
Phosphorylation of Srp1p, the yeast nuclear localization signal receptor, in vitro and in vivo.
1997,
Pubmed Azuma,
Isolation of a yeast protein kinase that is activated by the protein encoded by SRP1 (Srp1p) and phosphorylates Srp1p complexed with nuclear localization signal peptides.
1995,
Pubmed
,
Xenbase Bamba,
The GTPase Ran regulates chromosome positioning and nuclear envelope assembly in vivo.
2002,
Pubmed
,
Xenbase Ellenberg,
Nuclear membrane dynamics and reassembly in living cells: targeting of an inner nuclear membrane protein in interphase and mitosis.
1997,
Pubmed Foisner,
Inner nuclear membrane proteins and the nuclear lamina.
2001,
Pubmed Geles,
A role for Caenorhabditis elegans importin IMA-2 in germ line and embryonic mitosis.
2002,
Pubmed Gorjánácz,
Importin-alpha 2 is critically required for the assembly of ring canals during Drosophila oogenesis.
2002,
Pubmed Görlich,
Transport between the cell nucleus and the cytoplasm.
1999,
Pubmed Görlich,
Isolation of a protein that is essential for the first step of nuclear protein import.
1994,
Pubmed
,
Xenbase Gruss,
Ran induces spindle assembly by reversing the inhibitory effect of importin alpha on TPX2 activity.
2001,
Pubmed
,
Xenbase Harel,
Importin beta negatively regulates nuclear membrane fusion and nuclear pore complex assembly.
2003,
Pubmed
,
Xenbase Hartinger,
16-BAC/SDS-PAGE: a two-dimensional gel electrophoresis system suitable for the separation of integral membrane proteins.
1996,
Pubmed Hetzer,
Distinct AAA-ATPase p97 complexes function in discrete steps of nuclear assembly.
2001,
Pubmed
,
Xenbase Hetzer,
GTP hydrolysis by Ran is required for nuclear envelope assembly.
2000,
Pubmed
,
Xenbase Hetzer,
The Ran GTPase as a marker of chromosome position in spindle formation and nuclear envelope assembly.
2002,
Pubmed Holmer,
Inner nuclear membrane proteins: functions and targeting.
2001,
Pubmed Jäkel,
Importins fulfil a dual function as nuclear import receptors and cytoplasmic chaperones for exposed basic domains.
2002,
Pubmed Köcher,
Nanoelectrospray-based detection and sequencing of substoichiometric amounts of phosphopeptides in complex mixtures.
2003,
Pubmed Laemmli,
Cleavage of structural proteins during the assembly of the head of bacteriophage T4.
1970,
Pubmed Marshall,
Nuclear envelope assembly after mitosis.
1997,
Pubmed Matsusaka,
Mutations in fission yeast Cut15, an importin alpha homolog, lead to mitotic progression without chromosome condensation.
1998,
Pubmed Mattaj,
Sorting out the nuclear envelope from the endoplasmic reticulum.
2004,
Pubmed Nachury,
Importin beta is a mitotic target of the small GTPase Ran in spindle assembly.
2001,
Pubmed
,
Xenbase Quimby,
The small GTPase Ran: interpreting the signs.
2003,
Pubmed Shevchenko,
Mass spectrometric sequencing of proteins silver-stained polyacrylamide gels.
1996,
Pubmed Timinszky,
The importin-beta P446L dominant-negative mutant protein loses RanGTP binding ability and blocks the formation of intact nuclear envelope.
2002,
Pubmed Tirián,
P446L-importin-beta inhibits nuclear envelope assembly by sequestering nuclear envelope assembly factors to the microtubules.
2003,
Pubmed Walther,
RanGTP mediates nuclear pore complex assembly.
2003,
Pubmed
,
Xenbase Wiese,
Nuclear envelope assembly in Xenopus extracts visualized by scanning EM reveals a transport-dependent 'envelope smoothing' event.
1997,
Pubmed
,
Xenbase Yang,
Integral membrane proteins of the nuclear envelope are dispersed throughout the endoplasmic reticulum during mitosis.
1997,
Pubmed Zhang,
Chromatin-independent nuclear envelope assembly induced by Ran GTPase in Xenopus egg extracts.
2000,
Pubmed
,
Xenbase Zhang,
Role of importin-beta in the control of nuclear envelope assembly by Ran.
2002,
Pubmed
,
Xenbase
