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Gene Review

KPNA1  -  karyopherin alpha 1 (importin alpha 5)

Homo sapiens

Synonyms: IPOA5, Importin subunit alpha-5, Karyopherin subunit alpha-1, NPI-1, Nucleoprotein interactor 1, ...
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Disease relevance of KPNA1


High impact information on KPNA1

  • These results indicate that the extracellular signal-dependent nuclear transport of Stat1 is mediated by NPI-1, but not Rch1, in conjunction with beta subunit, and that these factors participate in, not only constitutive, but also the conditional nuclear import of proteins [3].
  • This domain is conserved in other SRP1-like proteins and its fusion to a cytoplasmic reporter protein is sufficient to promote complete nuclear import, circumventing the usual requirement for an NLS receptor interaction [4].
  • We have found that the karyopherins hSRP1 and hSRP1alpha are differentially expressed in various leukocyte cell lines and could be induced in normal human peripheral blood lymphocytes [5].
  • Furthermore, in HeLa cell crude cytosol, it was found that endogenous Rch1 binds to all the tested NLS substrates, while the binding of endogenous NPI-1 is restricted to only some NLSs, despite the fact that NPI-1 itself shows binding activity to a variety of NLSs [6].
  • The first step, which is to dock the NLS-containing protein to the nuclear pore, is carried out in part by a recently identified NLS receptor named Srp1/importin-alpha [7].

Biological context of KPNA1

  • Assignment of karyopherin alpha 1 (KPNA1) to human chromosome band 3q21 by in situ hybridization [8].
  • The karyopherin alpha NPI-1 (importin alpha5), a nuclear import adaptor, bound more strongly to Ser385-phosphorylated NLS than to any other phosphorylated or nonphosphorylated forms [2].
  • DNA sequence analysis revealed that the full-length cDNA, encoding rat KPNA1, was 4975 bp with a short 5'-untranslated region (UTR) of 70 bp, a putative coding sequence of 1617 bp, and an unusually long 3'-UTR of 3266 bp [9].
  • Exposure of various cell types to high glucose or mannose (25 mmol/L) led to increased expression of importins alpha3, alpha5/hSRP1, and alpha7 in different cultured cells, while up-regulation of other importin alpha isoforms was less consistent [10].
  • The phylogeny reveals three Kpna subfamilies with distinct, conserved gene structures, shedding light on the evolutionary origins of this multigene family in metazoa [11].

Anatomical context of KPNA1

  • A full-length cDNA clone of NPI-1 was generated from HeLa cell poly A + RNA [1].
  • We also demonstrate that Kpna genes are regulated in rat liver and isolated hepatocytes in a xenobiotic-specific manner for a number of chemically distinct liver growth agents [11].

Associations of KPNA1 with chemical compounds

  • The viral nucleoprotein, which had been partially purified from influenza A/PR/8/34 virus-infected embryonated eggs, could be coprecipitated from solution by glutathione agarose beads complexed with a bacterially expressed glutathione-S-transferase-NPI-1 fusion protein, confirming the results of the yeast genetic system [1].
  • Our results suggest involvement of KPNA1 in the striatal responses to denervation following 6-hydroxydopamine (6-OHDA)-induced lesion [9].
  • The characteristic hyperfine triplet is assigned in part to RCH2. radicals from glycine units, which constitute about one-third of the total amino acid components in collagen, and in part to RNHCO radicals [12].

Physical interactions of KPNA1

  • Interestingly, IFN-gamma-SV was also translocated to the nucleus and was also recovered intracellularly as a complex with the Stat1alpha importer NPI-1, like wild-type IFN-gamma [13].

Analytical, diagnostic and therapeutic context of KPNA1

  • Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis demonstrated that KPNA1 transcript existed in various adult tissues [9].
  • METHODS AND RESULTS: Using quantitative PCR, we have analysed Kpna transcript levels in 44 rat tissues; Kpna transcripts show a wide variation in their distribution both in absolute and relative terms, suggestive of specialized roles for each member [11].


  1. NPI-1, the human homolog of SRP-1, interacts with influenza virus nucleoprotein. O'Neill, R.E., Palese, P. Virology (1995) [Pubmed]
  2. Nuclear import of Epstein-Barr virus nuclear antigen 1 mediated by NPI-1 (Importin alpha5) is up- and down-regulated by phosphorylation of the nuclear localization signal for which Lys379 and Arg380 are essential. Kitamura, R., Sekimoto, T., Ito, S., Harada, S., Yamagata, H., Masai, H., Yoneda, Y., Yanagi, K. J. Virol. (2006) [Pubmed]
  3. Extracellular signal-dependent nuclear import of Stat1 is mediated by nuclear pore-targeting complex formation with NPI-1, but not Rch1. Sekimoto, T., Imamoto, N., Nakajima, K., Hirano, T., Yoneda, Y. EMBO J. (1997) [Pubmed]
  4. The conserved amino-terminal domain of hSRP1 alpha is essential for nuclear protein import. Weis, K., Ryder, U., Lamond, A.I. EMBO J. (1996) [Pubmed]
  5. Differential expression and sequence-specific interaction of karyopherin alpha with nuclear localization sequences. Nadler, S.G., Tritschler, D., Haffar, O.K., Blake, J., Bruce, A.G., Cleaveland, J.S. J. Biol. Chem. (1997) [Pubmed]
  6. Differential modes of nuclear localization signal (NLS) recognition by three distinct classes of NLS receptors. Miyamoto, Y., Imamoto, N., Sekimoto, T., Tachibana, T., Seki, T., Tada, S., Enomoto, T., Yoneda, Y. J. Biol. Chem. (1997) [Pubmed]
  7. The nuclear localization signal of lymphoid enhancer factor-1 is recognized by two differentially expressed Srp1-nuclear localization sequence receptor proteins. Prieve, M.G., Guttridge, K.L., Munguia, J.E., Waterman, M.L. J. Biol. Chem. (1996) [Pubmed]
  8. Assignment of karyopherin alpha 1 (KPNA1) to human chromosome band 3q21 by in situ hybridization. Ayala-Madrigal, M.L., Doerr, S., Ramírez-Dueñas, M.L., Hansmann, I. Cytogenet. Cell Genet. (2000) [Pubmed]
  9. Molecular cloning and characterization of rat karyopherin alpha 1 gene: structure and expression. Wang, B., Li, Z., Xu, L., Goggi, J., Yu, Y., Zhou, J. Gene (2004) [Pubmed]
  10. Increased importin alpha protein expression in diabetic nephropathy. Köhler, M., Buchwalow, I.B., Alexander, G., Christiansen, M., Shagdarsuren, E., Samoilova, V., Hartmann, E., Mervaala, E.M., Haller, H. Kidney Int. (2001) [Pubmed]
  11. Transcriptomic and phylogenetic analysis of Kpna genes: a family of nuclear import factors modulated in xenobiotic-mediated liver growth. Plant, K.E., Everett, D.M., Gordon Gibson, G., Lyon, J., Plant, N.J. Pharmacogenet. Genomics (2006) [Pubmed]
  12. Radicals generated by bone cutting and fracture. Symons, M.C. Free Radic. Biol. Med. (1996) [Pubmed]
  13. Nuclear translocation of IFN-gamma is an intrinsic requirement for its biologic activity and can be driven by a heterologous nuclear localization sequence. Subramaniam, P.S., Green, M.M., Larkin, J., Torres, B.A., Johnson, H.M. J. Interferon Cytokine Res. (2001) [Pubmed]
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