View source for Importin

<StructureSection load='1ee5' size='340' side='right' caption='Structure of yeast importin α NLS-binding domain (grey) complex with nucleoplasmin peptide (green) (PDB code [[1ee5]]).' scene=''>

== 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.  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]].

== Disease ==

== Relevance ==

== Structural highlights ==
</StructureSection>

==3D structures of importin==

Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}
{{#tree:id=OrganizedByTopic|openlevels=0|

*IPO-α

**[[1ial]] – mIPO NLS-binding domain – mouse<br />
**[[1bk5]] – yIPO NLS-binding domain - yeast<br />
**[[4tnm]] – IPO armadillo repeat domain – ''Arabidopsis thaliana''<br />

*''IPO-α complex with NLS peptide''

**[[1ejl]] – mIPO NLS-binding domain + SV40 large T antigen<br />
**[[1ejy]] – mIPO NLS-binding domain + nucleoplasmin <br />
**[[2ynr]] – mIPO NLS-binding domain + B54NLS <br />
**[[2yns]] – rIPO NLS-binding domain + B54NLS - rice<br />
**[[1bk6]] – yIPO NLS-binding domain + SV40 large T antigen<br />
**[[1ee4]] – yIPO NLS-binding domain (mutant) + c-Myc<br />
**[[1ee5]] – yIPO NLS-binding domain (mutant) + nucleoplasmin<br />
**[[1un0]], [[2c1t]] – yIPO NLS-binding domain (mutant) + Nup2<br />

*''IPO-α complex with protein''

**[[1wa5]] – yIPO NLS-binding domain + GTPase Ran + IPO-α re-exporter<br />

*IPO-α 1

**[[3wpt]] – hIPO NLS-binding domain - human<br />
**[[4b8j]] – rIPO <br />

*''IPO-α 1 complex with NLS peptide''

**[[4mz5]], [[4mz6]] – mIPO NLS-binding domain + dUTPase<br />
**[[4oih]] – mIPO NLS-binding domain + guanine nucleotide exchange factor SRM1<br />
**[[4b18]] – hIPO NLS-binding domain + telomerase reverse transcriptase<br />
**[[4wv6]] – hIPO NLS-binding domain + TFIID<br />
**[[4b8o]] – rIPO NLS-binding domain + SV40<br />
**[[4b8p]] – rIPO NLS-binding domain + A89<br />
**[[4bpl]] – rIPO NLS-binding domain + nucleoplasmin<br />
**[[4bqk]] – rIPO NLS-binding domain + VirD2<br />

*''IPO-α 1 complex with protein''

**[[2jdq]] – hIPO NLS-binding domain + polymerase basic protein  2 C terminal<br />
**[[3tj3]] – hIPO NLS-binding domain + Nup50 N terminal<br />
**[[2jdq]] – hIPO NLS-binding domain + telomerase reverse transcriptase peptide<br />
**[[4uaf]] – mIPO NLS-binding domain + influenza RNA polymerase<br />

*IPO-α 2

**[[3tpo]] – mIPO<br />
**[[1iq1]] – mIPO NLS-binding + autoinhibitory peptide domains<br />
**[[4e4v]] – hIPO NLS-binding domain (mutant) <br />

*''IPO-α 2 complex with NLS peptide''

**[[1pjm]] – mIPO NLS-binding domain + retinoblastoma-associated protein<br />
**[[1pjn]] – mIPO NLS-binding domain + histone-binding protein N1/N2<br />
**[[1q1s]], [[1q1t]] – mIPO NLS-binding domain + SV40 large T antigen<br />
**[[1y2a]], [[3q5u]] – mIPO NLS-binding domain + phospholipid scramblase <br />
**[[2c1m]] – mIPO NLS-binding domain + Nup50<br />
**[[3btr]] – mIPO NLS-binding domain + androgen receptor<br />
**[[3knd]] – mIPO NLS-binding domain + targeting protein for KXLP2<br />
**[[3l3q]] – mIPO NLS-binding domain + library peptide<br />
**[[3oqs]] – mIPO NLS-binding domain + CLIC4<br />
**[[3rz9]] – mIPO NLS-binding domain + KU80<br />
**[[3rzx]] – mIPO NLS-binding domain + KU70<br />
**[[3tpm]] – mIPO NLS-binding domain + MAL<br />
**[[3ve6]] – mIPO NLS-binding domain + Venezuelan equine encephalitis virus<br />
**[[3uvu]] – mIPO NLS-binding domain + flap endonuclease<br />
**[[3ukw]], [[3ukx]] – mIPO NLS-binding domain + BIMAX<br />
**[[3uky]], [[3ukz]], [[3ul0]] – mIPO NLS-binding domain + nuclear CAP-binding protein<br />
**[[3ul1]] – mIPO NLS-binding domain + nucleoplasmin <br />
**[[4htv]] – mIPO NLS-binding domain + capsid protein <br />
**[[4ba3]] – mIPO NLS-binding domain + A89NLS <br />
**[[3zio]], [[3zip]], [[3ziq]], [[3zir]] – mIPO NLS-binding domain + minor site-specific NLS <br />
**[[3zin]] – mIPO NLS-binding domain + nucleolar RNA helicase<br />

*''IPO-α 2 complex with protein''

**[[3fex]], [[3fey]] – mIPO NLS-binding domain + nuclear CAP-binding protein<br />

*IPO-α 3

**[[4uae]] – hIPO NLS-binding domain + influenza RNA polymerase<br />

*IPO-α 6 

**[[4u2x]] – hIPO C terminal + ebola VP24<br />

*IPO-α 7

**[[4uad]] – hIPO NLS-binding domain + influenza RNA polymerase<br />

*IPO-β 1 (karyopherin β 1)

**[[3nd2]] – yIPO <br />
**[[1gcj]] – mIPO N terminal<br />

*''IPO-β 1 complex with protein''

**[[1qgx]], [[1qgr]] – hIPO + IPO-α 2 IBB domain<br />
**[[1ibr]] – hIPO + GTPase Ran<br />
**[[2bku]], [[3ea5]] – yIPO + GTPase Ran<br />
**[[1f59]], [[1o6p]], [[1o6o]] – hIPO + FXFG nucleoporin repeats<br />
**[[1m5n]] – hIPO HEAT repeats 1-11 + parathyroid hormone-related protein NLS peptide<br />
**[[2p8q]], [[2q5d]], [[2qna]], [[3lww]] – hIPO + RNA U transporter N terminal<br />
**[[1qgr]], [[3w5k]] – hIPO + zinc finger protein SNAI1<br />
**[[2bpt]] – yIPO + Nup1<br />
**[[1ukl]] – mIPO + SREBP-2<br />

*IPO-β 2 (Transportin 1)

**[[2z5j]], [[2qmr]] – hIPO <br />

*''IPO-β 2 complex with protein''

**[[2h4m]], [[2ot8]], [[2z5n]] – hIPO + hnRNP peptide<br />
**[[2z5k]], [[2z5m]] – hIPO + nuclear RNA export factor peptide<br />
**[[2z5o]] – hIPO + JKTBP peptide<br />
**[[4fdd]], [[4jlq]], [[4oo6]] – hIPO + RNA binding protein peptide<br />
**[[4fq3]] – hIPO + FUS peptide<br />

*IPO-β 3 (Karyopherin β 3)

**[[3w3t]] – yIPO <br />
**[[3w3u]], [[3w3v]] – yIPO (mutant)<br />
**[[3w3w]] – yIPO + STE12P<br />
**[[3w3x]] – yIPO + PHO4<br />
**[[3w3y]] – yIPO + Nup53P<br />
**[[3w3z]] – yIPO + RANGTP<br />

*IPO-12 (Transportin-3)

**[[4c0p]] – hIPO <br />
**[[4c0o]] – hIPO + serine/arginine-rich splicing factor<br />
**[[4c0q]], [[4ol0]] – hIPO + GTPase Ran<br />

*IPO-13 (karyopherin 13)

**[[2x19]] – hIPO + GTPase Ran<br />
**[[2xwu]] – hIPO + UBC9<br />
**[[3zjy]] – hIPO + GTPase Ran + EIF-1A<br />
}}

== References ==
<references/>

[[Category:Topic Page]]