Chloride ion channel (CLC (for the family; specific channels include CLC-1, CLC-2, etc.))

Chloride ion channels are a diverse group of transmembrane proteins that selectively allow the passage of chloride ions across cellular membranes. They play essential roles in maintaining membrane potential, regulating cell volume, facilitating epithelial fluid secretion, modulating neuronal excitability, and acidifying intracellular organelles. The best-characterized families are the ClC family—which includes both classical channels such as ClC‑1 and ClC‑2 found at the plasma membrane as well as intracellular exchangers—and CFTR. Dysfunction or mutation in these channels leads to a range of human diseases including cystic fibrosis, myotonia congenita, epilepsy, macular degeneration, kidney stones and more. Drugs targeting these channels act by either enhancing their activity (“openers” like lubiprostone) or inhibiting them (“blockers” like NMD670). While they represent validated therapeutic targets with approved drugs on market—such as ivacaftor/lumacaftor for CF—challenges remain regarding selectivity due to structural similarities among subtypes.

Other names

ClC channelchloride channelCLCN (gene family)CFTR (for cystic fibrosis transmembrane conductance regulator subtype)voltage-gated chloride channel

Channel openers/potentiators increase chloride flux through the pore to restore or enhance physiological function. Channel blockers/inhibitors reduce chloride conductance to decrease excitability or secretion. Modulation via regulatory domains or associated proteins can alter gating properties or trafficking.