This entry represents the BTB (Broad-Complex, Tramtrack and Bric a brac)/POZ (poxvirus and zinc finger) domain found in the human potassium channel tetramerization domain-containing protein 1 (KCTD1) (, ) and similar sequences from vertebrates. This domain, also known as tetramerization (T1) domain, is a versatile protein-protein interaction motif that facilitates homodimerisation or heterodimerisation. KCTD family BTB domains can adopt a wide range of oligomerisation geometries, including homodimerisation, tetramerisation, and pentamerisation. The KCTD1 BTB domains form pentamers [].KCTD1 is a nuclear BTB/POZ domain-containing protein that acts as a transcriptional repressor and mediates protein-protein interactions through a BTB domain. It represses the transcriptional activity of AP-2 family members, including TFAP2A, TFAP2B and TFAP2C to various extent. It also functions as a novel inhibitor of the Wnt signalling pathway. Mutations in KCTD1 cause scalp-ear-nipple (SEN) syndrome [, , , , ].
