THE BTB DOMAIN, FOUND PRIMARILY IN ZINC-FINGER PROTEINS, DEFINES AN EVOLUTIONARILY CONSERVED FAMILY THAT INCLUDES SEVERAL DEVELOPMENTALLY-REGULATED GENES IN DROSOPHILA

The Drosophila bric a brac protein and the transcriptional regulators encoded by tramtrack and Broad-Complex contain a highly conserved doma in of approximate to 115 amino acids, which we have called the BTB dom ain. We have identified six additional Drosophila genes that encode th is domain. Five of these genes are developmentally regulated, and one of them appears to be functionally related to bric a brac. The BTB dom ain defines a gene family with an estimated 40 members in Drosophila. This domain is found primarily at the N terminus of zinc finger protei ns and is evolutionarily conserved from Drosophila to mammals.