bHLH proteins encoded by the Enhancer of split complex of Drosophila negatively interfere with transcriptional activation mediated by proneural genes

Mol Gen Genet. 1994 Sep 1;244(5):465-73. doi: 10.1007/BF00583897.


The Enhancer of split complex [E(SPL)-C] of Drosophila participates in the control of cell fate choice by uncommitted neuroectodermal cells in the embryo. It encodes seven proteins that belong to the basic helix-loop-helix (bHLH) family, six of which are expressed in very similar patterns in the neuroectoderm. Here we describe experiments aimed at unravelling the molecular basis of their function. We found that two products of the complex, HLH-M5 and ENHANCER OF SPLIT, are capable of binding as homo-and heterodimers to a sequence in the promoters of the Enhancer of split and achaete genes, called the N-box, which differs slightly from the consensus binding site (the E-box) for other bHLH proteins. In transient expression assays in cell culture, both proteins were found to attenuate the transcriptional activation mediated by the proneural bHLH proteins LETHAL OF SCUTE and DAUGHTERLESS at the Enhancer of split promoter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors
  • Cell Differentiation / genetics
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology*
  • Drosophila / embryology*
  • Drosophila / genetics
  • Drosophila Proteins*
  • Ectoderm / cytology
  • Embryo, Nonmammalian / cytology
  • Gene Expression Regulation
  • Genes, Insect*
  • Helix-Loop-Helix Motifs
  • Insect Hormones / genetics
  • Insect Hormones / physiology
  • Molecular Sequence Data
  • Nervous System / embryology*
  • Promoter Regions, Genetic
  • Repressor Proteins / chemistry
  • Repressor Proteins / genetics*
  • Repressor Proteins / physiology
  • Transcription Factors / antagonists & inhibitors*
  • Transcription Factors / genetics
  • Transcription Factors / physiology
  • Transcription, Genetic / physiology


  • Basic Helix-Loop-Helix Transcription Factors
  • DNA-Binding Proteins
  • Drosophila Proteins
  • E(spl)mdelta-HLH protein, Drosophila
  • Insect Hormones
  • Repressor Proteins
  • Transcription Factors
  • ac protein, Drosophila
  • l(1)sc protein, Drosophila