Abstract
The POU-IV or "Brn-3" class of POU-domain transcription factors is represented in Drosophila by I-POU and twin-of-I-POU, alternative splice products of the I-POU gene. I-POU has been previously reported to inhibit DNA binding by the POU-III class factor drifter/Cf1a via the formation of heterodimeric complexes. Here we report that expression of the I-POU/tI-POU message is maximal late in the embryonic phase of Drosophila development, and I-POU is the preferred splice variant. Although I-POU lacks two basic amino acid residues in the POU-homeodomain found in tI-POU and Brn-3.0, these three POU-IV class proteins exhibit very similar DNA-binding specificity. In contrast to previously published reports, the results presented here show no effect of I-POU on DNA binding by drifter, and no evidence for I-POU/drifter dimerization. These results suggest that the I-POU/tI-POU gene products function by transcriptional mechanisms similar to those of the homologous POU-IV class factors expressed in other species, not by unique inhibitory mechanism.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Alternative Splicing
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Amino Acid Sequence
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Animals
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Antennapedia Homeodomain Protein
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Base Sequence
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Binding Sites
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Conserved Sequence
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DNA / chemistry
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DNA / metabolism*
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DNA Primers
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DNA-Binding Proteins*
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Drosophila
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Drosophila Proteins
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Exons
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Homeodomain Proteins / biosynthesis
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Homeodomain Proteins / chemistry*
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Homeodomain Proteins / metabolism*
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Host Cell Factor C1
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Insect Hormones / chemistry
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Introns
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Mammals
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Molecular Sequence Data
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Nuclear Proteins*
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Octamer Transcription Factor-1
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Oligodeoxyribonucleotides
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Protein Structure, Secondary
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Sequence Homology, Amino Acid
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Transcription Factors / biosynthesis
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Transcription Factors / chemistry*
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Transcription Factors / metabolism*
Substances
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Antennapedia Homeodomain Protein
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Antp protein, Drosophila
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DNA Primers
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DNA-Binding Proteins
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Drosophila Proteins
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En protein, Drosophila
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Homeodomain Proteins
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Host Cell Factor C1
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Insect Hormones
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Nuclear Proteins
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Octamer Transcription Factor-1
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Oligodeoxyribonucleotides
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Transcription Factors
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DNA