In voltage-gated K+ channels this domain is responsible for subfamily-specific assembly of alpha-subunits into functional tetrameric channels [1]. In KCTD1 (Swiss:Q719H9) this domain functions as a transcriptional repressor [2]. It also mediates homomultimerisation of KCTD1 and interaction of KCTD1 with the transcription factor AP-2-alpha [2-3].

1: Zn2+-binding and molecular determinants of tetramerization in voltage-gated K+ channels. Bixby KA, Nanao MH, Shen NV, Kreusch A, Bellamy H, Pfaffinger PJ, Choe S; Nat Struct Biol 1999;6:38-43. PMID:9886290

2: Characterization and expression of a human KCTD1 gene containing the BTB domain, which mediates transcriptional repression and homomeric interactions. Ding XF, Luo C, Ren KQ, Zhang J, Zhou JL, Hu X, Liu RS, Wang Y, Gao X, Zhang J; DNA Cell Biol. 2008;27:257-265. PMID:18358072

3: The interaction of KCTD1 with transcription factor AP-2alpha inhibits its transactivation. Ding X, Luo C, Zhou J, Zhong Y, Hu X, Zhou F, Ren K, Gan L, He A, Zhu J, Gao X, Zhang J; J Cell Biochem. 2009;106:285-295. PMID:19115315