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ClC-1-like chloride channel proteins. This CD includes isoforms ClC-0, ClC-1, ClC-2 and ClC_K. ClC-1 is expressed in skeletal muscle and its mutation leads to both recessively and dominantly-inherited forms of muscle stiffness or myotonia. ClC-K is exclusively expressed in kidney. Similarly, mutation of ClC-K leads to nephrogenic diabetes insipidus in mice and Bartter's syndrome in human. These proteins belong to the ClC superfamily of chloride ion channels, which share the unique double-barreled architecture and voltage-dependent gating mechanism. The gating is conferred by the permeating anion itself, acting as the gating charge. This domain is found in the eukaryotic halogen ion (Cl-, Br- and I-) channel proteins, that perform a variety of functions including cell volume regulation, regulation of intracelluar chloride concentration, membrane potential stabilization, charge compensation necessary for the acidification of intracellular organelles and transepithelial chloride transport.