A Drosophila protein that imparts directionality on a chromatin insulator is an enhancer of position-effect variegation.
The suppressor of Hairy wing (su(Hw)) protein inhibits the function of transcriptional enhancers located distally from the promoter with respect to the location of su(Hw)-binding sites. This polarity is due to the ability of the su(Hw)-binding region to form a chromatin insulator. Mutations in modifier of mdg4 (mod(mdg4)) enhance the effect of su(Hw) by inhibiting the function of enhancers located on both sides of the su(Hw)-binding region. This inhibition results in a variegated expression pattern, and mutations in mod(mdg4) act as classical enhancers of position-effect variegation. The mod(mdg4) and su(Hw) proteins interact with each other. The mod(mdg4) protein controls the nature of the repressive effect of su(Hw): in the absence of mod(mdg4) protein, su(Hw) exerts a bidirectional silencing effect, whereas in the presence of mod(mdg4), the silencing effect is transformed into unidirectional repression.
Gerasimova
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TI
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Gdula
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DA
Gerasimov
D V
DV
Simonova
O
O
Corces
V G
VG
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D002843:Chromatin / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D017344:Genes, Insect; D016153:Genes, Suppressor; D016350:Leucine Zippers / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C101384:mod(mdg4) protein, Drosophila; C083738:su(Hw) protein, Drosophila