Fragments of the Fab-3 and Fab-4 Boundaries of the Drosophila melanogaster Bithorax Complex That Include CTCF Sites Are not Effective Insulators

Dokl Biochem Biophys. 2022 Feb;502(1):21-24. doi: 10.1134/S1607672922010069. Epub 2022 Mar 11.


The segment-specific regulatory domains of the Bithorax complex (BX-C), which consists of three homeotic genes Ubx, abd-A and Abd-B, are separated by boundaries that function as insulators. Most of the boundaries contain binding sites for the architectural protein CTCF, which is conserved for higher eukaryotes. As was shown previously, the CTCF sites determine the insulator activity of the boundaries of the Abd-B regulatory region. In this study, it was shown that fragments of the Fab-3 and Fab-4 boundaries of the abd-A regulatory region, containing CTCF binding sites, are not effective insulators.

Keywords: Abd-B; Fab-7; abd-A; architectural proteins; dCTCF; insulators; regulatory domain.

MeSH terms

  • Animals
  • Binding Sites
  • CCCTC-Binding Factor* / genetics
  • CCCTC-Binding Factor* / metabolism
  • Drosophila Proteins* / genetics
  • Drosophila Proteins* / metabolism
  • Drosophila melanogaster* / genetics
  • Drosophila melanogaster* / metabolism
  • Genes, Homeobox
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Insulator Elements
  • Transcription Factors / metabolism


  • CCCTC-Binding Factor
  • CTCF protein, Drosophila
  • Drosophila Proteins
  • Homeodomain Proteins
  • Transcription Factors
  • Ubx protein, Drosophila