A novel cis-regulatory element, the PTS, mediates an anti-insulator activity in the Drosophila embryo

Cell. 1999 Dec 10;99(6):567-75. doi: 10.1016/s0092-8674(00)81546-9.


The Abd-B Hox gene contains an extended 3' cis-regulatory region that is subdivided into a series of separate lab domains. The lab-7 domain activates Abd-B in parasegment 12 (ps12), whereas lab-8 controls expression in ps13. iab-7 is flanked by two insulators, Fab-7 and Fab-8, which are thought to prevent regulatory factors, such as Polycomb silencers, from influencing neighboring iab domains. This organization poses a potential paradox, since insulator DNAs can work in a dominant fashion to block enhancer-promoter interactions over long distances. Here, we present evidence for a novel cis-regulatory sequence located within lab-7, the promoter targeting sequence (PTS), which permits distal enhancers to overcome the blocking effects of Fab-8 and the heterologous su(Hw) insulator. We propose that the PTS converts dominant, long-range insulators into local regulatory elements that separate neighboring lab domains.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Drosophila / embryology*
  • Drosophila / genetics
  • Drosophila Proteins*
  • Enhancer Elements, Genetic
  • Genes, Homeobox / genetics*
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • In Situ Hybridization
  • Models, Genetic
  • Promoter Regions, Genetic
  • Regulatory Sequences, Nucleic Acid*


  • Abd-B proteins, Drosophila
  • Drosophila Proteins
  • Homeodomain Proteins