BTB (Broad-Complex, Tramtrack and Bric a brac)/POZ (poxvirus and zinc finger) domain found in BTB and CNC homolog 1 (BACH1)
BACH1, also called BTB-basic leucine zipper transcription factor 1, belongs to the cap 'n' collar (CNC) and basic leucine zipper (bZIP) factor family. It can act as repressor or activator. BACH1 is a heme-responsive transcriptional repressor of heme oxygenase (HO)-1. It represses genes involved in heme metabolism and oxidative stress response. It is also a negative regulator of nuclear factor erythroid 2-related factor 2 (Nrf2) that controls antioxidant response elements (ARE)-dependent gene expressions. BACH1 binds to NF-E2 binding sites in vitro, and plays important roles in coordinating transcription activation and repression by MafK. The BTB/POZ domain is a common protein-protein interaction motif of about 100 amino acids.