KCa3.1 | IK | SK4 | Intermediate Conductance Calcium-activated Potassium Channel Protein 4
Calcium-activated Potassium channels
Today, eight human calcium-activated channels are known: KCa1.1 (also known as BK or Maxi-K), KCa2.1 (also known as SK1), KCa2.2 (also known as SK2), KCa2.3 (also known as SK3) , KCa3.1 (also known as IK or SK4), KCa4.1, KCa4.2, KCa5.1
KCa channels are made up of two different subunits, alpha and beta. The alpha subunit contains six or seven trans-membrane regions and forms homo- or heter-tetramers. The beta subunit has a regulative function and contains 2 trans-membrane regions.
This family of ion channels is, for the most part, activated by intracellular Ca2+. However, some of these channels (the KCa4 and KCa5 channels) are responsive instead to other intracellular ligands, such as Na+, Cl−, and pH. Furthermore, multiple members of family are both ligand and voltage activated.