Abstract
Transcriptional activation by many eukaryotic sequence-specific regulators appears to be mediated through transcription factors which do not directly bind to DNA. BmFTZ-F1 is a silkworm counterpart of FTZ-F1, a sequence-specific activator of the fushi tarazu gene in Drosophila melanogaster. We report here the isolation of 18- and 22-kDa polypeptides termed MBF1 and MBF2, respectively, that form a heterodimer and mediate activation of in vitro transcription from the fushi tarazu promoter by BmFTZ-F1. Neither MBF1, MBF2, nor a combination of them binds to DNA. MBF1 interacts with BmFTZ-F1 and stabilizes the BmFTZ-F1-DNA complex. MBF1 also makes direct contact with TATA-binding protein (TBP). Both MBF1 and MBF2 are necessary to form a complex between BmFTZ-F1 and TBP. We propose a model in which MBF1 and MBF2 form a bridge between BmFTZ-F1 and TBP and mediate transactivation by stabilizing the protein-DNA interactions.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Base Sequence
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Binding Sites
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Bombyx / genetics
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Bombyx / metabolism*
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DNA / metabolism
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DNA-Binding Proteins / biosynthesis
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DNA-Binding Proteins / isolation & purification
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DNA-Binding Proteins / metabolism
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Drosophila Proteins
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Drosophila melanogaster / genetics
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Drosophila melanogaster / metabolism*
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Fushi Tarazu Transcription Factors
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Gene Expression
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Gene Expression Regulation*
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Homeodomain Proteins*
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Humans
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Insect Hormones / biosynthesis*
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Insect Hormones / genetics
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Insect Proteins
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Kinetics
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Models, Genetic
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Molecular Sequence Data
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Molecular Weight
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Receptors, Cytoplasmic and Nuclear
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Recombinant Proteins / biosynthesis
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Steroidogenic Factor 1
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TATA Box
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TATA-Box Binding Protein
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Transcription Factors / biosynthesis
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Transcription Factors / isolation & purification
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Transcription Factors / metabolism*
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Transcription, Genetic
Substances
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DNA-Binding Proteins
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Drosophila Proteins
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Fushi Tarazu Transcription Factors
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Homeodomain Proteins
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Insect Hormones
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Insect Proteins
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Receptors, Cytoplasmic and Nuclear
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Recombinant Proteins
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Steroidogenic Factor 1
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TATA-Box Binding Protein
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Transcription Factors
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ftz protein, Drosophila
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nuclear hormone receptor FTZ-F1, Bombyx mori
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nuclear hormone receptor FTZ-F1, Drosophila
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DNA