ID:IMA1_HUMAN DESCRIPTION: RecName: Full=Importin subunit alpha-1; AltName: Full=Karyopherin subunit alpha-1; AltName: Full=Nucleoprotein interactor 1; Short=NPI-1; AltName: Full=RAG cohort protein 2; AltName: Full=SRP1-beta; 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. SUBUNIT: Heterodimer; with KPNB1. Interacts with ANP32E. Interacts with ZIC3 (By similarity). Interacts with the nucleoprotein of influenza A viruses. Binds to HCMV (human cytomegalovirus) UL84, HIV-1 Vpr and to ebolavirus VP24. Interacts with APEX1 and RAG1. Interacts with CTNNBL1 (via its N-terminal). Interacts with AICDA (via its NLS). SUBCELLULAR LOCATION: Cytoplasm. Nucleus. TISSUE SPECIFICITY: Expressed ubiquitously. DOMAIN: Consists of an N-terminal hydrophilic region, a hydrophobic central region composed of 10 repeats, and a short hydrophilic C-terminus. The N-terminal hydrophilic region contains the importin beta binding domain (IBB domain), which is sufficient for binding importin beta and essential for nuclear protein import. DOMAIN: The IBB domain is thought to act as an intrasteric autoregulatory sequence by interacting with the internal autoinhibitory NLS. Binding of KPNB1 probably overlaps the internal NLS and contributes to a high affinity for cytoplasmic NLS-containing cargo substrates. After dissociation of the importin/substrate complex in the nucleus the internal autohibitory NLS contributes to a low affinity for nuclear NLS- containing proteins (By similarity). DOMAIN: The major and minor NLS binding sites are mainly involved in recognition of simple or bipartite NLS motifs. Structurally located within in a helical surface groove they contain several conserved Trp and Asn residues of the corresponding third helices (H3) of ARM repeats which mainly contribute to binding (By similarity). PTM: Polyubiquitinated in the presence of RAG1 (in vitro). SIMILARITY: Belongs to the importin alpha family. SIMILARITY: Contains 10 ARM repeats. SIMILARITY: Contains 1 IBB domain.
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on P52294
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
Gene Ontology (GO) Annotations with Structured Vocabulary
Molecular Function: GO:0005515 protein binding GO:0008139 nuclear localization sequence binding GO:0008565 protein transporter activity GO:0061608 nuclear import signal receptor activity
Biological Process: GO:0000018 regulation of DNA recombination GO:0006309 apoptotic DNA fragmentation GO:0006606 protein import into nucleus GO:0006607 NLS-bearing protein import into nucleus GO:0015031 protein transport GO:0016032 viral process GO:0019054 modulation by virus of host process GO:0075733 intracellular transport of virus
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Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
