FTZ-F1 beta, a novel member of the Drosophila nuclear receptor family.

The Drosophila melanogaster gene FTZ-F1 beta, encoding a novel member of the steroid/thyroid hormone receptor gene superfamily, was isolated by cross-hybridization with a complementary DNA for the Drosophila nuclear receptor, FTZ-F1 (Lavorgna et al., 1991). The cDNA deduced protein sequence for FTZ-F1 beta displays significant amino acid identity with other vertebrate and invertebrate nuclear receptors, most notably with FTZ-F1. Also, bacterially expressed FTZ-F1 beta protein binds to a FTZ-F1 binding site found in the zebra stripe promoter element of the segmentation gene fushi tarazu (ftz). Northern blot analysis detected FTZ-F1 beta expression at all stages of the Drosophila life cycle including a possible maternal component. In situ hybridization in whole-mounted embryos localized transcripts for FTZ-F1 beta evenly expressed throughout the blastodermal layer in early embryos. At later stages of development strong FTZ-F1 beta expression is observed in both the brain and ventral chord structures as well as in the hindgut. Temporal and spatial expression patterns of the FTZ-F1 beta gene suggest that it may have multiple roles in early embryogenesis, neurogenesis, and in the adult. Furthermore, the identification of FTZ-F1 beta as a nuclear receptor family member suggests that an as yet undiscovered FTZ-F1 beta specific ligand is involved in Drosophila development.