Biochemistry, Chloride Channels

Excerpt

Ion channels are used by cells to regulate many cellular functions, from action potential conduction to water balance, which is sometimes achieved by using a single ion in the setting of different channels types. Although ion channels are described as transmembrane proteins that have a “pore” which allows for the diffusion of specific ions across a concentration gradient, other channels involved in ion transport include antiporters (exchange), symporters (cotransport in the same direction) and pumps (use energy from hydrolysis of ATP). Chloride channels are a remarkable example of this since they are involved in the control of transepithelial transport, membrane excitability, and the regulation of cell volume and intracellular and intraorganelle pH. All of this is achievable by the use of the many different types of chloride channels, of which there are three major families: the voltage-gated chloride channels, the cystic fibrosis transmembrane conductance regulator (CFTR) and related channels, and the ligand-gated channels activated by gamma-aminobutyric acid (GABA) and glycine.