THE SPALT-RELATED GENE OF DROSOPHILA-MELANOGASTER IS A MEMBER OF AN ANCIENT GENE FAMILY, DEFINED BY THE ADJACENT, REGION-SPECIFIC HOMEOTIC GENE SPALT

We report the full coding sequence of a new Drosophila gene, spalt-rel ated, which is homologous and adjacent to the region-specific homeotic gene, spalt. Both genes have three widely spaced sets of C2H2 zinc fi nger motifs, but spalt-related encodes a fourth pair of C-terminal fin gers resembling the Xenopus homologue, Xsal-1. The degrees of sequence divergence among all three members of this family are comparable, sug gesting that the Drosophila genes originated from an ancient gene dupl ication. The spalt-related gene is expressed with quantitative variati ons from mid-embryogenesis (8-12 h) to the adult stage, but not in ova ries or early embryos. Expression is localized to limited parts of the body, including specific cell populations in the nervous system. In t he wing disc, spalt and spalt-related are expressed in indistinguishab le domains; in the nervous system and some other organs the expression patterns extensively overlap but are not identical, indicating that t he genes have partially diverged in terms of developmental regulation. A characteristic central set of zinc fingers specifically binds to an AIT-rich consensus sequence, defining some DNA binding properties of this ancient family of nuclear factors.