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Gene Review

PSE1  -  Pse1p

Saccharomyces cerevisiae S288c

Synonyms: Importin subunit beta-3, KAP121, Karyopherin subunit beta-3, Karyopherin-121, Protein secretion enhancer 1, ...
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Disease relevance of PSE1

  • The core protein of hepatitis C virus is imported into the nucleus by transport receptor Kap123p but inhibits Kap121p-dependent nuclear import of yeast AP1-like transcription factor in yeast cells [1].

High impact information on PSE1

  • These changes allow a transport inhibitory nucleoporin, Nup53p, to bind the karyopherin Kap121p specifically during mitosis, slowing its movement through the NPC and inducing cargo release [2].
  • Yeast strains that possess defects in the function of Kap121p or the fidelity of the inhibitory pathway are delayed in mitosis [2].
  • We show that the related protein Pse1p is also a karyopherin and can functionally substitute for Kap123p; both are capable of specifically directing a ribosomal nuclear localization signal reporter to the nucleus in vivo [3].
  • Pse1 binds directly to Pho4 and is required for its import in vivo [4].
  • Phosphorylation of Pho4 inhibits its interaction with Pse1, providing a mechanism by which phosphorylation may regulate import of Pho4 in vivo [4].

Biological context of PSE1


Anatomical context of PSE1


Associations of PSE1 with chemical compounds

  • This Pdr1-NLS sequence, absent in Pdr3, although rich in serine and tyrosine, is different from the Pse1-dependent nuclear localization signal (NLS) of Pho4 [7].
  • The activity of Pse1, when expressed in yeast, was not sensitive to the antibiotic cerulenin, which is an effective inhibitor of fatty acid synthesis and elongation [11].

Physical interactions of PSE1

  • In an in vitro assay, we showed that Yap1p could directly bind to Pse1p and that this interaction was dissociated by Ran-GTP [5].
  • At the NPC, Nup53p exists in two separate complexes, one of which is capable of interacting with Kap121p and another that is bound to Nup170p [9].
  • Aft1p could also directly bind to Pse1p and was dissociated from the complex by Ran-GTP in vitro [12].
  • Biochemical studies indicate that Pse1p binds to a region of Abf1p upstream of CS1 in a RanGTP-sensitive manner, suggesting that Abf1p has a second distinct NLS and can be imported into the nucleus by several overlapping pathways [13].

Regulatory relationships of PSE1

  • This suggests that the interaction between Aft1p and Pse1p is not a critical step that controls the iron-regulated nucleo-cytoplasmic transport of Aft1p [12].

Other interactions of PSE1

  • In pse1-1 cells, which bear a temperature-sensitive mutation of PSE1, Aft1p was misdirected to the cytoplasm during iron starvation at the restrictive temperature [12].
  • PSE1/KAP121 overexpression also improves the import of the hydrophobic protein Atm1p, an ABC transporter of the mitochondrial inner membrane [8].
  • L25 binds to Yrb4p and Pse1p and is released by Gsp1p-GTP [6].
  • Kap121p can be released from Nup53p by the GTP bound form of the small GTPase Ran [14].
  • We conclude from our in vivo and in vitro experiments that import of the essential histones is mediated mainly by the essential importin Pse1p, while the non-essential Kap114p functions in a parallel import pathway for H2A and H2B [15].


  1. The core protein of hepatitis C virus is imported into the nucleus by transport receptor Kap123p but inhibits Kap121p-dependent nuclear import of yeast AP1-like transcription factor in yeast cells. Isoyama, T., Kuge, S., Nomoto, A. J. Biol. Chem. (2002) [Pubmed]
  2. Cell cycle regulated transport controlled by alterations in the nuclear pore complex. Makhnevych, T., Lusk, C.P., Anderson, A.M., Aitchison, J.D., Wozniak, R.W. Cell (2003) [Pubmed]
  3. A distinct nuclear import pathway used by ribosomal proteins. Rout, M.P., Blobel, G., Aitchison, J.D. Cell (1997) [Pubmed]
  4. Phosphorylation regulates association of the transcription factor Pho4 with its import receptor Pse1/Kap121. Kaffman, A., Rank, N.M., O'Shea, E.K. Genes Dev. (1998) [Pubmed]
  5. Nuclear import of the yeast AP-1-like transcription factor Yap1p is mediated by transport receptor Pse1p, and this import step is not affected by oxidative stress. Isoyama, T., Murayama, A., Nomoto, A., Kuge, S. J. Biol. Chem. (2001) [Pubmed]
  6. Yrb4p, a yeast ran-GTP-binding protein involved in import of ribosomal protein L25 into the nucleus. Schlenstedt, G., Smirnova, E., Deane, R., Solsbacher, J., Kutay, U., Görlich, D., Ponstingl, H., Bischoff, F.R. EMBO J. (1997) [Pubmed]
  7. Pse1/Kap121-dependent nuclear localization of the major yeast multidrug resistance (MDR) transcription factor Pdr1. Delahodde, A., Pandjaitan, R., Corral-Debrinski, M., Jacq, C. Mol. Microbiol. (2001) [Pubmed]
  8. Overexpression of yeast karyopherin Pse1p/Kap121p stimulates the mitochondrial import of hydrophobic proteins in vivo. Corral-Debrinski, M., Belgareh, N., Blugeon, C., Claros, M.G., Doye, V., Jacq, C. Mol. Microbiol. (1999) [Pubmed]
  9. Karyopherins in nuclear pore biogenesis: a role for Kap121p in the assembly of Nup53p into nuclear pore complexes. Lusk, C.P., Makhnevych, T., Marelli, M., Aitchison, J.D., Wozniak, R.W. J. Cell Biol. (2002) [Pubmed]
  10. Nuclear import of Spo12p, a protein essential for meiosis. Chaves, S.R., Blobel, G. J. Biol. Chem. (2001) [Pubmed]
  11. Cloning and functional characterisation of an enzyme involved in the elongation of Delta6-polyunsaturated fatty acids from the moss Physcomitrella patens. Zank, T.K., Zähringer, U., Beckmann, C., Pohnert, G., Boland, W., Holtorf, H., Reski, R., Lerchl, J., Heinz, E. Plant J. (2002) [Pubmed]
  12. Pse1p mediates the nuclear import of the iron-responsive transcription factor Aft1p in Saccharomyces cerevisiae. Ueta, R., Fukunaka, A., Yamaguchi-Iwai, Y. J. Biol. Chem. (2003) [Pubmed]
  13. Functional and physical interactions between autonomously replicating sequence-binding factor 1 and the nuclear transport machinery. Loch, C.M., Mosammaparast, N., Miyake, T., Pemberton, L.F., Li, R. Traffic (2004) [Pubmed]
  14. Specific binding of the karyopherin Kap121p to a subunit of the nuclear pore complex containing Nup53p, Nup59p, and Nup170p. Marelli, M., Aitchison, J.D., Wozniak, R.W. J. Cell Biol. (1998) [Pubmed]
  15. The histones H2A/H2B and H3/H4 are imported into the yeast nucleus by different mechanisms. Greiner, M., Caesar, S., Schlenstedt, G. Eur. J. Cell Biol. (2004) [Pubmed]
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