BTB/POZ domain

The BTB/POZ domain (BTB for BR-C, ttk and bab or POZ for Pox virus and Zinc finger) is a structural domain found in proteins across the domain Eukarya. Given its prevalence in eukaryotes and its absence in Archaea and bacteria, it likely arose after the origin of eukaryotes. While primarily a protein-protein interaction domain, some BTB domains have additional functionality in transcriptional regulation, cytoskeletal mobility, protein ubiquitination and degradation, and ion channel formation and operation. BTB domains have traditionally been classified by the other structural features present in the protein.