InterPro domain: IPR027353

The bromodomain and extraterminal (BET) proteins are a class of transcriptional regulators whose members can be found in animals, plants and fungi. BET proteins are involved in diverse cellular phenomena such as meiosis, cell-cycle control, and homeosis and have been suggested to modulatechromatin structure and affect transcription via a sequence-independent mechanism. BET proteins are defined as having one (plants) or two (animals/yeast) bromodomains and an Extra Terminal (ET)domain. The ET domain consists of three separate regions, only one of which, the N-terminal ET (NET) domain is conserved in all BET proteins. The function of the NET domain is assumed to be protein binding [ 1 , 2 , 3 , 4 ].

The structure of the NET domain comprises three alpha-helices and a characteristic loop region of an irregular but well-defined structure. The NET structure has an acidic patch that forms a continuousridge with a hydrophobic cleft. which may interact with other proteins and/or DNA [ 5 ].

Some proteins known to contain a NET domain include:

• Human RING3 (now designated Brd2)
• Murine MCAP (now designated Brd4)
• Drosophila Fsh
• Yeast Bdf1 and Bdf2
• Arabidopsis imbibition-inducible (IMB1), whichplays a role in abscisic acid (ABA) and phytochrome A (phyA) mediated responses of seed germination.

1. The yeast BDF1 gene encodes a transcription factor involved in the expression of a broad class of genes including snRNAs. Nucleic Acids Res. 22, 5332-40
2. You bet-cha: a novel family of transcriptional regulators. Front. Biosci. 6, D1008-18
3. IMB1, a bromodomain protein induced during seed imbibition, regulates ABA- and phyA-mediated responses of germination in Arabidopsis. Plant J. 35, 787-99
4. Solution structure of the extraterminal domain of the bromodomain-containing protein BRD4. Protein Sci. 17, 2174-9