This domain can be found at the N terminus of voltage-gated potassium channel proteins, where represents a cytoplasmic tetramerisation domain (T1) involved in assembly of alpha-subunits into functional tetrameric channels []. This domain can also be found in proteins that are not potassium channels, like KCTD1 (potassium channel tetramerisation domain-containing protein 1). KCTD1 is though to be a nuclear protein that functions as a transcriptional repressor. In KCTD1, the T1-type BTB domain mediates homomeric protein-protein interactions [, ].
This entry represents the BTB (Broad-Complex, Tramtrack and Bric a brac)/POZ (poxvirus and zinc finger) domain, also known as tetramerization (T1) domain, found in KCTD15 proteins from vertebrates. It is a versatile protein-protein interaction motif that facilitates homodimerization or heterodimerization. The BTB domains from KCTD family members can adopt a wide range of oligomerization geometries, including homodimerization, tetramerization, and pentamerization. The KCTD1 BTB domains, closely related to KCTD15, form pentamers [, ].BTB/POZ domain-containing protein KCTD15 (potassium channel tetramerization domain-containing protein 15) plays a role in the regulation of neural crest (NC) formation and other steps in embryonic development. It inhibits AP2 transcriptional activity by interacting with its activation domain [, , ].
