Polycomb and trithorax group proteins mediate the function of a chromatin insulator.
Chromatin boundaries or insulator elements affect the interaction between enhancers and promoters. The gypsy insulator contains two proteins, Su(Hw) and Mod(mdg4). Both proteins colocalize on several hundred sites on polytene chromosomes and are distributed in a punctated pattern in the nuclear matrix. Mutations in mod(mdg4) have properties characteristic of a trxG gene. In addition, mutations in trxG genes enhance insulator effects on adjacent enhancers, whereas mutations in Pc have the opposite result. These alterations correlate with changes in the pattern of nuclear localization of insulator components. The results suggest a model in which PcG and TrxG proteins regulate insulator function by establishing higher order domains of chromatin organization required for the assembly of functional insulators at the nuclear matrix.
Gerasimova
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Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Corces
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D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry; D002843:Chromatin / Q000235:genetics; D002875:Chromosomes / Q000502:physiology; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D004742:Enhancer Elements, Genetic / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox / Q000502:physiology; D019476:Insect Proteins / Q000235:genetics*; D008297:Male; D009154:Mutation; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics*; D063150:Polycomb Repressive Complex 1; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000032:analysis / Q000235:genetics; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*
D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; C066770:Pc protein, Drosophila; D012097:Repressor Proteins; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C101384:mod(mdg4) protein, Drosophila; C083738:su(Hw) protein, Drosophila; D063150:Polycomb Repressive Complex 1