bHLH proteins encoded by the Enhancer of split complex of Drosophila negatively interfere with transcriptional activation mediated by proneural genes.
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.
Oellers
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Institut für Entwicklungsbiologie, Universität zu Köln, Germany.
Dehio
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M
Knust
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E
D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004330:Drosophila / Q000196:embryology* / Q000235:genetics; D029721:Drosophila Proteins; D004475:Ectoderm / Q000166:cytology; D004625:Embryo, Nonmammalian / Q000166:cytology; D005786:Gene Expression Regulation; D017344:Genes, Insect; D018257:Helix-Loop-Helix Motifs; D007301:Insect Hormones / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009420:Nervous System / Q000196:embryology*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic / Q000502:physiology
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D007301:Insect Hormones; D012097:Repressor Proteins; D014157:Transcription Factors; C084530:E(spl)mdelta-HLH protein, Drosophila; C089199:ac protein, Drosophila; C089200:l(1)sc protein, Drosophila