Importin: Difference between revisions

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== Function ==
== Function ==


'''Importins''' (IPO) mediate the import of cellular proteins into the nucleus by binding to the '''N'''uclear '''L'''ocalization '''S'''ignal (NLS).  IPO has 2 subunits: α and β.  '''IPO-α''' is an adaptor protein which binds the NLS<ref>PMID:9759490</ref>.  IPOs can contain one or two NLS motifs.  '''IPO-α''' contains several armadillo repeats with two NLS-binding sites and an IPO-β binding (IBB) site.  '''IPO-β''' contains 19 HEAT (solenoid domain) repeats.  Many nuclear proteins contain Phe-Gly sequences which can bind to HEAT repeats and thus be transported.  See also [[Protein Transport Membrane Protein]].
'''Importins''' (IPO) mediate the import of cellular proteins into the nucleus by binding to the '''N'''uclear '''L'''ocalization '''S'''ignal (NLS).  IPO has 2 subunits: α and β.  '''IPO-α''' is an adaptor protein which binds the NLS<ref>PMID:9759490</ref>.  IPOs can contain one or two NLS motifs.   
*'''IPO-α''' contains several armadillo repeats with two NLS-binding sites and an IPO-β binding (IBB) site.   
*'''IPO-β''' contains 19 HEAT (solenoid domain) repeats.  Many nuclear proteins contain Phe-Gly sequences which can bind to HEAT repeats and thus be transported.   
See also [[Protein Transport Membrane Protein]].


== Disease ==
== Disease ==

Revision as of 12:44, 2 July 2024


Function

Importins (IPO) mediate the import of cellular proteins into the nucleus by binding to the Nuclear Localization Signal (NLS). IPO has 2 subunits: α and β. IPO-α is an adaptor protein which binds the NLS[1]. IPOs can contain one or two NLS motifs.

  • IPO-α contains several armadillo repeats with two NLS-binding sites and an IPO-β binding (IBB) site.
  • IPO-β contains 19 HEAT (solenoid domain) repeats. Many nuclear proteins contain Phe-Gly sequences which can bind to HEAT repeats and thus be transported.

See also Protein Transport Membrane Protein.

Disease

IPO-α isoform expression is altered in many kinds of cancer.

Relevance

Specific IPO-α isoforms are critical in nerve regenerative response after injury. Loss of IPO-α expression in aging myocardial cells could make recovery after heart disease in elderly patients more difficult[2].

Structural highlights

3D structures of importin

Importin 3D structures


Structure of yeast importin α NLS-binding domain (grey) complex with nucleoplasmin peptide (green) (PDB code 1ee5).

Drag the structure with the mouse to rotate

ReferencesReferences

  1. ↑ Mattaj IW, Englmeier L. Nucleocytoplasmic transport: the soluble phase. Annu Rev Biochem. 1998;67:265-306. PMID:9759490 doi:http://dx.doi.org/10.1146/annurev.biochem.67.1.265
  2. ↑ Pumroy RA, Cingolani G. Diversification of importin-alpha isoforms in cellular trafficking and disease states. Biochem J. 2015 Feb 15;466(1):13-28. doi: 10.1042/BJ20141186. PMID:25656054 doi:http://dx.doi.org/10.1042/BJ20141186

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