Binding site-dependent direct activation and repression of in vitro transcription by Drosophila homeodomain proteins.
Fushi tarazu and engrailed are two of the genes required for proper segmentation of the Drosophila embryo. Their protein products Fushi tarazu and Engrailed (Ftz and En) each contain a homeodomain and have been shown to act as transcriptional regulators in transient expression experiments in a Drosophila cell culture system. We used an in vitro transcription system to test whether the effects of Ftz and En on transcription were direct or indirect. Purified Ftz directly activates in vitro transcription by binding to homeodomain binding sites inserted upstream of the TATA box of the Drosophila hsp70 promoter. Equimolar amounts of purified En repress this activation by competition with Ftz for binding to these sites. These results indicate that Ftz and En act directly as transcription factors and suggest that such homeodomain proteins regulate development by combinatorial transcriptional control.
Ohkuma
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Y
Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021.
Horikoshi
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M
Roeder
R G
RG
Desplan
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C
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002846:Chromatography, Affinity; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D018398:Homeodomain Proteins; D007301:Insect Hormones / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics* / Q000302:isolation & purification; D014157:Transcription Factors / Q000235:genetics* / Q000302:isolation & purification; D014158:Transcription, Genetic
D029721:Drosophila Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D007301:Insect Hormones; D015345:Oligonucleotide Probes; D012097:Repressor Proteins; D014157:Transcription Factors; C497169:ftz protein, Drosophila