 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, further complicating the description of this family.The KCa channel α subunits have six or seven transmembrane segments, similar to the KV channels but occasionally with an additional N-terminal transmembrane helix.