The BTB/POZ domain of the regulatory proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) interacts with the novel Drosophila TAF(II) factor BIP2/dTAF(II)155.

The BTB/POZ domain is an evolutionarily conserved protein-protein interaction domain present in the N-terminal region of numerous transcription factors involved in development, chromatin remodeling, and human cancers. This domain is involved in homomeric and heteromeric associations with other BTB/POZ domains. The Drosophila BTB/POZ proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) are developmentally regulated transcription factors which are involved in pattern formation along the proximo-distal axis of the leg and antenna, in the morphogenesis of the adult ovaries, and in the control of sexually dimorphic characters. We have identified partners of the BAB1 protein by using the two-hybrid system. The characterization of one of these proteins, called BIP2 for BAB Interacting Protein 2, is presented. BIP2 is a novel Drosophila TATA-box Protein Associated Factor (TAF(II)), also named dTAF(II)155. We show that the BTB/POZ domains of BAB1 and BAB2 are sufficient to mediate a direct interaction with BIP2/dTAF(II)155. This provides a direct link between these BTB/POZ transcription factors and the basal transcriptional machinery. We discuss the implications of the interaction between a BTB/POZ domain and a TAF(II) for the molecular mechanisms of transcriptional control mediated by BTB/POZ transcription factors. Copyright 2001 Academic Press.