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Importin

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== Function ==
== Function ==
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'''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. Proteins can contain one or two NLS motifs. IPO-α contains several armadillo repeats with two NLS-binding sites and an IPO-β binding site (IBB). IPO-β contains 19 HEAT repeats. Many nuclear proteins contain Phe-Gly sequences which can bind to HEAT repeats and thus be transported. See also [[Protein Transport Membrane Protein]].
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'''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 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 ==
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IPO-α isoform expression is altered in many kinds of cancer.
== Relevance ==
== Relevance ==
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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<ref>PMID:25656054</ref>.
== Structural highlights ==
== Structural highlights ==

Revision as of 11:02, 27 March 2016

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

3D structures of importin

Updated on 27-March-2016

References

  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

Proteopedia Page Contributors and Editors (what is this?)

Michal Harel, Joel L. Sussman

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