Similar DNA recognition properties of alternatively spliced Drosophila POU factors
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 a unique inhibitory mechanism.
Footnotes
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↵ * To whom reprint requests should be addressed at: Department of Psychiatry, University of California at San Diego, School of Medicine 0603, 9500 Gilman Drive, La Jolla, CA 92093-0603. e-mail: eturner{at}UCSD.edu.
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Michael G. Rosenfeld, University of California at San Diego, La Jolla, CA
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Abbreviations: I-POU, inhibitory POU; tI-POU, twin of I-POU; EMSA, electrophoretic mobility-shift assay; GST, glutathione S-transferase; BMH, bis-maleimidohexane.
- Copyright © 1996, The National Academy of Sciences of the USA
