Similar DNA recognition properties of alternatively spliced Drosophila POU factors.
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.
Turner
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Department of Psychiatry, University of California at San Diego, La Jolla 92093-0603, USA. eturner@UCSD.edu
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D051943:Antennapedia Homeodomain Protein; D001483:Base Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D004268:DNA-Binding Proteins; D004330:Drosophila; D029721:Drosophila Proteins; D005091:Exons; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D051863:Host Cell Factor C1; D007301:Insect Hormones / Q000737:chemistry; D007438:Introns; D008322:Mammals; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; D009838:Oligodeoxyribonucleotides; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*
D051943:Antennapedia Homeodomain Protein; C497974:Antp protein, Drosophila; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D051863:Host Cell Factor C1; D007301:Insect Hormones; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D004247:DNA