Calcium-activated potassium channel
This family of ion channels is, for the most part, activated by intracellular Ca2+ and contains 8 members. It should be noted, however, that some of these channels (the KCa4 and KCa5 channels) are responsive instead to intracellular Na+ and Cl-. Furthermore, the KCa1 family is both Ca2+ and voltage activated, further complicating the description of this family. The KCa channel α subunits have six transmembrane segments similar to the KVs, except KCa1, in which the N-terminus makes a seventh pass across the membrane to end up outside the cell. The α subunits make homo- and hetero-tetrameric complexes.
Below is a list of the 8 known calcium-activated potassium channel grouped according to sequence homology of transmembrane hydrophobic cores:
- Kca1.x : Kca1.1 (KCNMA1)
- Kca2.x : Kca2.1 (KCNN1), Kca2.2 (KCNN2), Kca2.3 (KCNN3)
- Kca3.x: Kca3.1 (KCNN4)
- Kca4.x: Kca4.1 (KCNT1), Kca4.2 (KCNT2)
- Kca5.x: Kca5.1 (KCNMC1)