Family 1.A.13 - The Epithelial Chloride Channel Family        

Family ID: 52601

Mammals have multiple isoforms of epithelial chloride channel proteins. The first member of this family to be characterized was a respiratory epithelium, Ca 2+-regulated, chloride channel protein isolated from bovine tracheal apical membranes. It was biochemically characterized as a 140 kDa complex. The purified complex when reconstituted in a planar lipid bilayer behaved as an anion-selective channel. It was regulated by Ca 2+ via a calmodulin kinase II-dependent mechanism. When the cRNA was injected into Xenopus oocytes, an outward rectifying, DIDS-sensitive, anion conductance was measured. A related gene, Lu-ECAM, was cloned from the bovine aortic endothelial cell line, BAEC. It is expressed in the lung and spleen but not in the trachea. Homologues are found in several mammals, and at least three paralogues(hCaCC-1-3) are present in humans, each with different tissue distributions.