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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.   | 
|  | + | *'''IPO-4''' binds histones H3 and H4 and histone chaperone ASF1 for nuclear import<ref>PMID:36103578</ref>.   | 
|  | + | *'''IPO-7'''  drives the nuclear import of the regulator of mechanotransduction pathway YAP<ref>PMID:35246520</ref>.  | 
|  | + | *'''IPO-9''' binds histones H2A and H2B for nuclear import<ref>PMID:30855230</ref>. | 
|  | + | *'''IPO-13''' has a role in oxidative stress-dependent nuclear export<ref>PMID:34625540</ref>. | 
|  | + |   | 
|  | + | See also [[Protein Transport Membrane Protein]]. | 
|  |  |  |  | 
|  | == Disease == |  | == Disease == | 
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|  |  |  |  | 
|  | == Structural highlights == |  | == Structural highlights == | 
| - | </StructureSection> |  | 
|  |  |  |  | 
|  | ==3D structures of importin== |  | ==3D structures of importin== | 
|  | + | [[Importin 3D structures]] | 
|  |  |  |  | 
| - | Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}
 | + | </StructureSection> | 
| - | {{#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 />
 | + |  | 
| - | **[[5h2x]], [[5h2w]] – yIPO NLS-binding domain + ubiquitin-like specific protease<br />
 | + |  | 
| - | **[[4xzr]] – yIPO NLS-binding domain + HEH1<br />
 | + |  | 
| - | **[[4pvz]] – yIPO NLS-binding domain + HEH2<br />
 | + |  | 
| - | **[[4rxh]] – NcIPO NLS-binding domain + SV40 large T antigen – ''Neurospora crassa''<br />
 | + |  | 
| - | **[[5vqi]] – NcIPO NLS-binding domain + NIT2<br />
 | + |  | 
| - |   | + |  | 
| - | *''IPO-α complex with protein''
 | + |  | 
| - |   | + |  | 
| - | **[[1wa5]] – yIPO NLS-binding domain + GTPase Ran + IPO-α re-exporter<br />
 | + |  | 
| - | **[[5t94]] – yIPO NLS-binding domain + guanine nucleotide exchange factor <br />
 | + |  | 
| - | **[[5mfm]] – yIPO NLS-binding domain + YIIIM6AII <br />
 | + |  | 
| - |   | + |  | 
| - | *IPO-α 1
 | + |  | 
| - |   | + |  | 
| - | **[[3wpt]] – hIPO NLS-binding domain - human<br />
 | + |  | 
| - | **[[4b8j]] – rIPO <br />
 | + |  | 
| - | **[[6bvt]] – mIPO NLS-binding domain <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 />
 | + |  | 
| - | **[[5svz]] – mIPO NLS-binding domain + TAT NLS motif<br />
 | + |  | 
| - | **[[5wum]], [[5wun]], [[5x8n]] – mIPO NLS-binding domain + Epstein Barr antigen<br />
 | + |  | 
| - | **[[5huw]] – mIPO NLS-binding domain + HSVI large terminase<br />
 | + |  | 
| - | **[[5huy]] – mIPO NLS-binding domain + HSMV small terminase<br />
 | + |  | 
| - | **[[5hhg]], [[5fc8]] – mIPO NLS-binding domain + dengue 2 NS5<br />
 | + |  | 
| - | **[[5ekg]], [[5ekf]], [[5e6q]] – mIPO NLS-binding domain + XPG2<br />
 | + |  | 
| - | **[[5d5k]] – mIPO NLS-binding domain + PARP 2<br />
 | + |  | 
| - | **[[5ctt]] – mIPO NLS-binding domain + SART3/TIP110<br />
 | + |  | 
| - | **[[5b56]] – mIPO NLS-binding domain + HIV-1 VPR<br />
 | + |  | 
| - | **[[4zdu]] – mIPO NLS-binding domain + influenza nucleoprotein<br />
 | + |  | 
| - | **[[4yi0]] – mIPO NLS-binding domain + Nup121<br />
 | + |  | 
| - | **[[5klr]], [[5klt]] – mIPO NLS-binding domain + NLS <br />
 | + |  | 
| - | **[[5k9s]] – mIPO NLS-binding domain + HNF-b <br />
 | + |  | 
| - | **[[4b18]] – hIPO NLS-binding domain + telomerase reverse transcriptase<br />
 | + |  | 
| - | **[[4wv6]] – hIPO NLS-binding domain + TFIID<br />
 | + |  | 
| - | **[[6bw0]] – hIPO NLS-binding domain + Nipa virus peptide<br />
 | + |  | 
| - | **[[6bw1]] – hIPO NLS-binding domain + Hendra virus peptide<br />
 | + |  | 
| - | **[[5w41]] – mIPO NLS-binding domain + Zika virus peptide <br />
 | + |  | 
| - | **[[5v5o]], [[5v5p]] – mIPO NLS-binding domain + influenza virus peptide <br />
 | + |  | 
| - | **[[5umz]] – mIPO NLS-binding domain + TNRC6A peptide <br />
 | + |  | 
| - | **[[5u5p]], [[5u5r]] – mIPO NLS-binding domain + MLH1 peptide <br />
 | + |  | 
| - | **[[5gxw]] – mIPO NLS-binding domain + NUMA peptide <br />
 | + |  | 
| - | **[[5w4e]], [[5w4f]], [[5w4g]] – hIPO NLS-binding domain + polymerase peptide<br />
 | + |  | 
| - | **[[5h43]] – hIPO NLS-binding domain + histone acetyltransferase KAT8<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
 | + |  | 
| - |   | + |  | 
| - | **[[6bvz]] – hIPO NLS-binding domain <br />
 | + |  | 
| - | **[[4uae]] – hIPO NLS-binding domain + influenza RNA polymerase<br />
 | + |  | 
| - | **[[6bw9]], [[6bwa]], [[6bwb]] – hIPO NLS-binding domain + Hendra virus peptide<br />
 | + |  | 
| - | **[[6bvv]] – hIPO NLS-binding domain + Nipa virus peptide<br />
 | + |  | 
| - | **[[5xzx]] – hIPO NLS-binding domain + RAN-binding protein peptide<br />
 | + |  | 
| - | **[[5tbk]] – hIPO NLS-binding domain + regulator of chromosome condensation <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 
 | + |  | 
| - |   | + |  | 
| - | **[[4xrk]] – IPO – ''Chaetomium thermophilum'' <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 />
 | + |  | 
| - | **[[5owu]] – 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 />
 | + |  | 
| - | **[[5yvg]], [[5yvh]] – hIPO + FUS <br />
 | + |  | 
| - | **[[5vyh]], [[5vyi]] – hIPO + FUS peptide<br />
 | + |  | 
| - | **[[4fq3]] – hIPO + FUS peptide<br />
 | + |  | 
| - | **[[5tqc]] – hIPO + RPL4 peptide<br />
 | + |  | 
| - | **[[5j3v]] – hIPO + histone H3 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 />
 | + |  | 
| - | **[[5h2v]] – yIPO + ubiquitin-like specific protease<br />
 | + |  | 
| - | **[[4zj7]] – yIPO + CDC14<br />
 | + |  | 
| - |   | + |  | 
| - | *IPO-4B
 | + |  | 
| - |   | + |  | 
| - | **[[5xah]] – hIPO residues 668-1081  <br />
 | + |  | 
| - | **[[5xbk]] – hIPO residues 668-1081 + histone H3 peptide <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 == |