Members of this family are found in the cytoplasmic N-terminus of KCNMB2, the beta-2 subunit of large conductance calcium and voltage-activated potassium channels. They are responsible for the fast inactivation of these channels [1].

1: NMR structure of the "ball-and-chain" domain of KCNMB2, the beta 2-subunit of large conductance Ca2+- and voltage-activated potassium channels. Bentrop D, Beyermann M, Wissmann R, Fakler B; J Biol Chem. 2001;276:42116-42121. PMID:11517232