Importin subunit beta-1 - P70168 (IMB1_MOUSE)

 

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Function
Functions in nuclear protein import, either in association with an adapter protein, like an importin-alpha subunit, which binds to nuclear localization signals (NLS) in cargo substrates, or by acting as autonomous nuclear transport receptor. Acting autonomously, serves itself as NLS receptor. 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. Mediates autonomously the nuclear import of ribosomal proteins RPL23A, RPS7 and RPL5. Binds to a beta-like import receptor binding (BIB) domain of RPL23A. In association with IPO7 mediates the nuclear import of H1 histone. In vitro, mediates nuclear import of H2A, H2B, H3 and H4 histones. In case of HIV-1 infection, binds and mediates the nuclear import of HIV-1 Rev. Imports SNAI1 and PRKCI into the nucleus. UniProt
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Subunit Structure
Forms a complex with an importin alpha subunit. Forms a heterodimer with IPO7. Interacts with IPO7, SNUPN, RPL23A and XPO1. The KPNB1/IPO7 heterodimer interacts with H1 histone. Interacts with H2A, H2B, H3 and H4 histones (By similarity). Component of an import snRNP complex composed of KPNB1, SNUPN, SMN1 and ZNF259. Component of a nuclear export receptor complex composed of KPNB1, Ran, SNUPN and XPO1. Binds to HIV-1 Rev and Tat. Interacts with HTLV-1 Rex. Interacts with SRY. Interacts with PRKCI/atypical protein kinase C iota (By similarity). Interacts with KPNA7. Interacts with SNAI1 (via zinc fingers) and SNAI2 (via zinc fingers) (By similarity). Interacts with SLC35G1 and STIM1 (By similarity). Interacts with DCAF8. Interacts with RAN (PubMed:25946333). UniProt
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Data in green originates from UniProtKB  
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Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
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  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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