Illustration of a human acid-sensitive outwardly rectifying anion channel (ASOR), a type of proton-activated chloride channel, in its activated conformation. This channel is found in both the outer and inner membrane of almost all human cells. It responds to changes in pH, becoming activated when the extracellular environment becomes very acidic. It plays a role in acid-induced cell death and the shrinkage of vesicles that transport extracellular fluid into a cell.