brahma: a regulator of Drosophila homeotic genes structurally related to the yeast transcriptional activator SNF2/SWI2.

The brahma (brm) gene is required for the activation of multiple homeotic genes in Drosophila. Loss-of-function brm mutations suppress mutations in Polycomb, a repressor of homeotic genes, and cause developmental defects similar to those arising from insufficient expression of the homeotic genes of the Antennapedia and Bithorax complexes. The brm gene encodes a 1638 residue protein that is similar to SNF2/SWI2, a protein involved in transcriptional activation in yeast, suggesting possible models for the role of brm in the transcriptional activation of homeotic genes. In addition, both brm and SNF2 contain a 77 amino acid motif that is found in other Drosophila, yeast, and human regulatory proteins and may be characteristic of a new family of regulatory proteins.