The transport of molecules between the nucleus and the cytoplasm in eukaryotic cells is mediated by the nuclear pore complex (NPC), which consists of 60-100 proteins. Small molecules (up to 70 kD) can pass through the nuclear pore by nonselective diffusion while larger molecules are transported by an active process. The protein encoded by this gene belongs to the importin alpha family, and is involved in nuclear protein import. [provided by RefSeq, Jan 2009]
Function:
Functions in nuclear protein import as an adapter protein for nuclear receptor KPNB1. Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Docking of the importin/substrate complex to the nuclear pore complex (NPC) is mediated by KPNB1 through binding to nucleoporin FxFG repeats and the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism. At the nucleoplasmic side of the NPC, Ran binds to importin-beta and the three components separate and importin-alpha and -beta are re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran from importin. The directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus. In vitro, mediates the nuclear import of human cytomegalovirus UL84 by recognizing a non-classical NLS. Recognizes NLSs of influenza A virus nucleoprotein probably through ARM repeats 7-9.
Subcellular Location:
Cytoplasm. Nucleus.
Tissue Specificity:
Ubiquitous. Highest levels in heart and skeletal muscle.
Similarity:
Belongs to the importin alpha family.
Contains 10 ARM repeats.
Contains 1 IBB domain.
SWISS:
O00505
Gene ID:
3839
Database links:
Entrez Gene: 3839 Human
Entrez Gene: 418870 Chicken
Entrez Gene: 540719 Cow
Entrez Gene: 16648 Mouse
Entrez Gene: 396715 Pig
Entrez Gene: 361055 Rat
Entrez Gene: 706925 Rhesus monkey
Omim: 601892 Human
SwissProt: O00505 Human
SwissProt: O35344 Mouse
Unigene: 527919 Human
Unigene: 25548 Mouse
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