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Gene Review

Iswi  -  Imitation SWI

Drosophila melanogaster

Synonyms: ACF, CG8625, CHRAC, CHRAC 140 kDa subunit, Chromatin-remodeling complex ATPase chain Iswi, ...
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High impact information on Iswi

  • Iswi protein alone is able to translocates along naked DNA in an ATP-dependent manner forming small DNA loops and changing at the same time the supercoiling degree [1].
  • These findings indicate that histone H3 K56 acetylation at the entry-exit gate enables recruitment of the SWI/SNF nucleosome remodeling complex and so regulates gene activity [2] .
  • Drosophila NURF is an ATP-dependent chromatin remodeling complex that contains ISWI, a member of the SWI2/SNF2 family of ATPases [3] .
  • However, the directionality of the CHRAC- and ISWI-induced nucleosome movements differed drastically, indicating that the geometry of the native complex modulates the activity of its catalytic core [4] .
  • The ISWI protein is localized to the cell nucleus and is expressed throughout Drosophila development at levels as high as 100,000 molecules/cell [5] .
  • SNF/SWI homologs have now been identified in Drosophila, mice and humans, suggesting a conserved role in transcriptional activation [6] .

Biological context of Iswi


Anatomical context of Iswi


Associations of Iswi with chemical compounds

  • The interaction of Acf1 with ISWI requires a DDT domain, which has been found in a variety of transcription and chromatin-remodeling factors [16] .
  • Functional Differentiation of SWI/SNF Remodelers in Transcription and Cell Cycle Control [17] .
  • The prevalence of serine amino acids at all specificity determining positions suggests that ARIDs within SWI/SNF-related complexes will interact with DNA non-sequence specifically [18] .

Physical interactions of Iswi


Regulatory relationships of Iswi


Other interactions of Iswi

  • ACF (ATP-utilizing chromatin assembly and remodeling factor) catalyzes the ATP-dependent assembly of periodic nucleosome arrays in vitro, and consists of Acf1 and the ISWI ATPase [20] .
  • Hormone-response Genes Are Direct in Vivo Regulatory Targets of Brahma (SWI/SNF) Complex Function [21] .
  • The iswi mutant germline stem cells are lost rapidly because of defects in responding to bone morphogenetic protein niche signals and in repressing differentiation, whereas the dom mutant somatic stem cells are lost because of defective self-renewal [12] .
  • Interestingly, although the Imitation Switch (ISWI) remodelers are potent nucleosome spacing factors, they are dispensable for transcriptional activation by Zeste [22]Ref.
  • Receptor binding to minichromosomes recruits ISWI and NURF38, but not brahma [23] .

Analytical, diagnostic and therapeutic context of Iswi

  • The Xenopus BRG1-like protein elutes at a Mr of approximately 2 000 000 on Superose HR6trade mark size-exclusion chromatography, indicating that it is part of a larger complex, as are all other known SWI/SNF proteins [24] .


  1. ATP-dependent looping of DNA by ISWI. WikiGenes. Publication
  2. Acetylation in histone H3 globular domain regulates gene expression in yeast. Xu, F., Zhang, K., Grunstein, M. Cell (2005) [Pubmed]
  3. ATP-dependent histone octamer sliding mediated by the chromatin remodeling complex NURF. Hamiche, A., Sandaltzopoulos, R., Gdula, D.A., Wu, C. Cell (1999) [Pubmed]
  4. Nucleosome movement by CHRAC and ISWI without disruption or trans-displacement of the histone octamer. Längst, G., Bonte, E.J., Corona, D.F., Becker, P.B. Cell (1999) [Pubmed]
  5. ISWI, a member of the SWI2/SNF2 ATPase family, encodes the 140 kDa subunit of the nucleosome remodeling factor. Tsukiyama, T., Daniel, C., Tamkun, J., Wu, C. Cell (1995) [Pubmed]
  6. The SNF/SWI family of global transcriptional activators. Carlson, M., Laurent, B.C. Curr. Opin. Cell Biol. (1994) [Pubmed]
  7. ACF, an ISWI-containing and ATP-utilizing chromatin assembly and remodeling factor. Ito, T., Bulger, M., Pazin, M.J., Kobayashi, R., Kadonaga, J.T. Cell (1997) [Pubmed]
  8. Dual functions of largest NURF subunit NURF301 in nucleosome sliding and transcription factor interactions. Xiao, H., Sandaltzopoulos, R., Wang, H.M., Hamiche, A., Ranallo, R., Lee, K.M., Fu, D., Wu, C. Mol. Cell (2001) [Pubmed]
  9. Two histone fold proteins, CHRAC-14 and CHRAC-16, are developmentally regulated subunits of chromatin accessibility complex (CHRAC). Corona, D.F., Eberharter, A., Budde, A., Deuring, R., Ferrari, S., Varga-Weisz, P., Wilm, M., Tamkun, J., Becker, P.B. EMBO J. (2000) [Pubmed]
  10. DNA supercoiling factor contributes to dosage compensation in Drosophila. Furuhashi, H., Nakajima, M., Hirose, S. Development (2006) [Pubmed]
  11. The putative SWI/SNF complex subunit BRAHMA activates flower homeotic genes in Arabidopsis thaliana. Hurtado, L., Farrona, S., Reyes, J.C. Plant Mol. Biol. (2006) [Pubmed]
  12. Stem cell self-renewal controlled by chromatin remodeling factors. Xi, R., Xie, T. Science (2005) [Pubmed]
  13. Structure and partial amino acid sequence of calf thymus DNA topoisomerase II: comparison with other type II enzymes. Austin, C.A., Barot, H.A., Margerrison, E.E., Turcatti, G., Wingfield, P., Hayes, M.V., Fisher, L.M. Biochem. Biophys. Res. Commun. (1990) [Pubmed]
  14. The ISWI chromatin-remodeling protein is required for gene expression and the maintenance of higher order chromatin structure in vivo. Deuring, R., Fanti, L., Armstrong, J.A., Sarte, M., Papoulas, O., Prestel, M., Daubresse, G., Verardo, M., Moseley, S.L., Berloco, M., Tsukiyama, T., Wu, C., Pimpinelli, S., Tamkun, J.W. Mol. Cell (2000) [Pubmed]
  15. SALL1 expression in the human pituitary-adrenal/gonadal axis. Ma, Y., Chai, L., Cortez, S.C., Stopa, E.G., Steinhoff, M.M., Ford, D., Morgan, J., Maizel, A.L. J. Endocrinol. (2002) [Pubmed]
  16. Binding of Acf1 to DNA involves a WAC motif and is important for ACF-mediated chromatin assembly. Fyodorov, D.V., Kadonaga, J.T. Mol. Cell. Biol. (2002) [Pubmed]
  17. Functional Differentiation of SWI/SNF Remodelers in Transcription and Cell Cycle Control. Moshkin, Y.M., Mohrmann, L., van Ijcken, W.F., Verrijzer, C.P. Mol. Cell. Biol. (2007) [Pubmed]
  18. The structure of the Dead ringer-DNA complex reveals how AT-rich interaction domains (ARIDs) recognize DNA. Iwahara, J., Iwahara, M., Daughdrill, G.W., Ford, J., Clubb, R.T. EMBO J. (2002) [Pubmed]
  19. Chromatin remodeling mediated by Drosophila GAGA factor and ISWI activates fushi tarazu gene transcription in vitro. Okada, M., Hirose, S. Mol. Cell. Biol. (1998) [Pubmed]
  20. Acf1 confers unique activities to ACF/CHRAC and promotes the formation rather than disruption of chromatin in vivo. Fyodorov, D.V., Blower, M.D., Karpen, G.H., Kadonaga, J.T. Genes Dev. (2004) [Pubmed]
  21. Hormone-response Genes Are Direct in Vivo Regulatory Targets of Brahma (SWI/SNF) Complex Function. Zraly, C.B., Middleton, F.A., Dingwall, A.K. J. Biol. Chem. (2006) [Pubmed]
  22. The Drosophila brahma complex is an essential coactivator for the trithorax group protein zeste. Kal, A.J., Mahmoudi, T., Zak, N.B., Verrijzer, C.P. Genes Dev. (2000) [Pubmed]
  23. Two-step synergism between the progesterone receptor and the DNA-binding domain of nuclear factor 1 on MMTV minichromosomes. Di Croce, L., Koop, R., Venditti, P., Westphal, H.M., Nightingale, K.P., Corona, D.F., Becker, P.B., Beato, M. Mol. Cell (1999) [Pubmed]
  24. Characterization of a chromatin remodelling activity in Xenopus oocytes. Gelius, B., Wade, P., Wolffe, A., Wrange, O., Ostlund Farrants, A.K. Eur. J. Biochem. (1999) [Pubmed]
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