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Karyopherin (importin) beta 1
Protein KPNB1 PDB 1f59.png
PDB rendering based on 1f59.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols KPNB1 ; IMB1; IPO1; IPOB; Impnb; NTF97
External IDs OMIM602738 MGI107532 HomoloGene1707 ChEMBL: 1741199 GeneCards: KPNB1 Gene
RNA expression pattern
PBB GE KPNB1 213803 at tn.png
PBB GE KPNB1 208974 x at tn.png
PBB GE KPNB1 208975 s at tn.png
More reference expression data
Species Human Mouse
Entrez 3837 16211
Ensembl ENSG00000108424 ENSMUSG00000001440
UniProt Q14974 P70168
RefSeq (mRNA) NM_001276453 NM_008379
RefSeq (protein) NP_001263382 NP_032405
Location (UCSC) Chr 17:
45.73 – 45.76 Mb
Chr 11:
97.16 – 97.19 Mb
PubMed search [1] [2]

Importin subunit beta-1 is a protein that in humans is encoded by the KPNB1 gene.[1][2]

Nucleocytoplasmic transport, a signal- and energy-dependent process, takes place through nuclear pore complexes embedded in the nuclear envelope. The import of proteins containing a classical nuclear localization signal (NLS) requires the NLS import receptor, a heterodimer of importin alpha and beta subunits. Each of these subunits are part of the karyopherin family of proteins. Importin alpha binds the NLS-containing cargo in the cytoplasm and importin beta docks the complex at the cytoplasmic side of the nuclear pore complex. In the presence of nucleoside triphosphates and the small GTP binding protein Ran, the complex moves into the nuclear pore complex and the importin subunits dissociate. Importin alpha enters the nucleoplasm with its passenger protein and importin beta remains at the pore. Interactions between importin beta and the FG repeats of nucleoporins are essential in translocation through the pore complex. The protein encoded by this gene is a member of the importin beta family.[3]


KPNB1 has been shown to interact with NUP98,[4][5] Karyopherin alpha 1,[6][7] KPNA3,[6][8] Karyopherin alpha 2,[6][9][10] SMN1,[11] Parathyroid hormone-related protein,[12][13] Nucleoporin 62,[7][14] RANBP2,[14][15][16] Ran (biology),[7][17][18] RANBP1,[15][18] NUP50,[19] P53,[20] NUP153[14][21][22] and Mothers against decapentaplegic homolog 3.[23]


  1. ^ Chi NC, Adam EJ, Adam SA (August 1995). "Sequence and characterization of cytoplasmic nuclear protein import factor p97". J Cell Biol 130 (2): 265–74. doi:10.1083/jcb.130.2.265. PMC 2199936. PMID 7615630. 
  2. ^ Gorlich D, Kostka S, Kraft R, Dingwall C, Laskey RA, Hartmann E, Prehn S (September 1995). "Two different subunits of importin cooperate to recognize nuclear localization signals and bind them to the nuclear envelope". Curr Biol 5 (4): 383–92. doi:10.1016/S0960-9822(95)00079-0. PMID 7627554. 
  3. ^ "Entrez Gene: KPNB1 karyopherin (importin) beta 1". 
  4. ^ Moroianu, J; Blobel G; Radu A (September 1997). "RanGTP-mediated nuclear export of karyopherin alpha involves its interaction with the nucleoporin Nup153". Proc. Natl. Acad. Sci. U.S.A. (UNITED STATES) 94 (18): 9699–704. doi:10.1073/pnas.94.18.9699. ISSN 0027-8424. PMC 23253. PMID 9275187. 
  5. ^ Bonifaci, N; Moroianu J; Radu A; Blobel G (May 1997). "Karyopherin beta2 mediates nuclear import of a mRNA binding protein". Proc. Natl. Acad. Sci. U.S.A. (UNITED STATES) 94 (10): 5055–60. doi:10.1073/pnas.94.10.5055. ISSN 0027-8424. PMC 24630. PMID 9144189. 
  6. ^ a b c Köhler, M; Speck C; Christiansen M; Bischoff F R; Prehn S; Haller H; Görlich D; Hartmann E (November 1999). "Evidence for distinct substrate specificities of importin alpha family members in nuclear protein import". Mol. Cell. Biol. (UNITED STATES) 19 (11): 7782–91. ISSN 0270-7306. PMC 84838. PMID 10523667. 
  7. ^ a b c Percipalle, P; Clarkson W D; Kent H M; Rhodes D; Stewart M (March 1997). "Molecular interactions between the importin alpha/beta heterodimer and proteins involved in vertebrate nuclear protein import". J. Mol. Biol. (ENGLAND) 266 (4): 722–32. doi:10.1006/jmbi.1996.0801. ISSN 0022-2836. PMID 9102465. 
  8. ^ Nachury, M V; Ryder U W; Lamond A I; Weis K (January 1998). "Cloning and characterization of hSRP1 gamma, a tissue-specific nuclear transport factor". Proc. Natl. Acad. Sci. U.S.A. (UNITED STATES) 95 (2): 582–7. doi:10.1073/pnas.95.2.582. ISSN 0027-8424. PMC 18463. PMID 9435235. 
  9. ^ Nagoshi, E; Yoneda Y (April 2001). "Dimerization of sterol regulatory element-binding protein 2 via the helix-loop-helix-leucine zipper domain is a prerequisite for its nuclear localization mediated by importin beta". Mol. Cell. Biol. (United States) 21 (8): 2779–89. doi:10.1128/MCB.21.8.2779-2789.2001. ISSN 0270-7306. PMC 86908. PMID 11283257. 
  10. ^ Kutay, U; Bischoff F R; Kostka S; Kraft R; Görlich D (September 1997). "Export of importin alpha from the nucleus is mediated by a specific nuclear transport factor". Cell (UNITED STATES) 90 (6): 1061–71. doi:10.1016/S0092-8674(00)80372-4. ISSN 0092-8674. PMID 9323123. 
  11. ^ Narayanan, Usha; Ospina Jason K; Frey Mark R; Hebert Michael D; Matera A Gregory (July 2002). "SMN, the spinal muscular atrophy protein, forms a pre-import snRNP complex with snurportin1 and importin beta". Hum. Mol. Genet. (England) 11 (15): 1785–95. doi:10.1093/hmg/11.15.1785. ISSN 0964-6906. PMC 1630493. PMID 12095920. 
  12. ^ Cingolani, Gino; Bednenko Janna; Gillespie Matthew T; Gerace Larry (December 2002). "Molecular basis for the recognition of a nonclassical nuclear localization signal by importin beta". Mol. Cell (United States) 10 (6): 1345–53. doi:10.1016/S1097-2765(02)00727-X. ISSN 1097-2765. PMID 12504010. 
  13. ^ Lam, M H; Hu W; Xiao C Y; Gillespie M T; Jans D A (March 2001). "Molecular dissection of the importin beta1-recognized nuclear targeting signal of parathyroid hormone-related protein". Biochem. Biophys. Res. Commun. (United States) 282 (2): 629–34. doi:10.1006/bbrc.2001.4607. ISSN 0006-291X. PMID 11401507. 
  14. ^ a b c Ben-Efraim, I; Gerace L (January 2001). "Gradient of increasing affinity of importin beta for nucleoporins along the pathway of nuclear import". J. Cell Biol. (United States) 152 (2): 411–7. doi:10.1083/jcb.152.2.411. ISSN 0021-9525. PMC 2199621. PMID 11266456. 
  15. ^ a b Yaseen, N R; Blobel G (September 1999). "GTP hydrolysis links initiation and termination of nuclear import on the nucleoporin nup358". J. Biol. Chem. (UNITED STATES) 274 (37): 26493–502. doi:10.1074/jbc.274.37.26493. ISSN 0021-9258. PMID 10473610. 
  16. ^ Delphin, C; Guan T; Melchior F; Gerace L (December 1997). "RanGTP targets p97 to RanBP2, a filamentous protein localized at the cytoplasmic periphery of the nuclear pore complex". Mol. Biol. Cell (UNITED STATES) 8 (12): 2379–90. doi:10.1091/mbc.8.12.2379. ISSN 1059-1524. PMC 25714. PMID 9398662. 
  17. ^ Kutay, U; Izaurralde E; Bischoff F R; Mattaj I W; Görlich D (March 1997). "Dominant-negative mutants of importin-beta block multiple pathways of import and export through the nuclear pore complex". EMBO J. (ENGLAND) 16 (6): 1153–63. doi:10.1093/emboj/16.6.1153. ISSN 0261-4189. PMC 1169714. PMID 9135132. 
  18. ^ a b Plafker, K; Macara I G (May 2000). "Facilitated nucleocytoplasmic shuttling of the Ran binding protein RanBP1". Mol. Cell. Biol. (UNITED STATES) 20 (10): 3510–21. doi:10.1128/MCB.20.10.3510-3521.2000. ISSN 0270-7306. PMC 85643. PMID 10779340. 
  19. ^ Lindsay, Mark E; Plafker Kendra; Smith Alicia E; Clurman Bruce E; Macara Ian G (August 2002). "Npap60/Nup50 is a tri-stable switch that stimulates importin-alpha:beta-mediated nuclear protein import". Cell (United States) 110 (3): 349–60. doi:10.1016/S0092-8674(02)00836-X. ISSN 0092-8674. PMID 12176322. 
  20. ^ Akakura, S; Yoshida M; Yoneda Y; Horinouchi S (May 2001). "A role for Hsc70 in regulating nucleocytoplasmic transport of a temperature-sensitive p53 (p53Val-135)". J. Biol. Chem. (United States) 276 (18): 14649–57. doi:10.1074/jbc.M100200200. ISSN 0021-9258. PMID 11297531. 
  21. ^ Nakielny, S; Shaikh S; Burke B; Dreyfuss G (April 1999). "Nup153 is an M9-containing mobile nucleoporin with a novel Ran-binding domain". EMBO J. (ENGLAND) 18 (7): 1982–95. doi:10.1093/emboj/18.7.1982. ISSN 0261-4189. PMC 1171283. PMID 10202161. 
  22. ^ Kehlenbach, R H; Gerace L (June 2000). "Phosphorylation of the nuclear transport machinery down-regulates nuclear protein import in vitro". J. Biol. Chem. (UNITED STATES) 275 (23): 17848–56. doi:10.1074/jbc.M001455200. ISSN 0021-9258. PMID 10749866. 
  23. ^ Xiao, Z; Liu X; Lodish H F (August 2000). "Importin beta mediates nuclear translocation of Smad 3". J. Biol. Chem. (UNITED STATES) 275 (31): 23425–8. doi:10.1074/jbc.C000345200. ISSN 0021-9258. PMID 10846168. 

Further reading[edit]