ClC family tree. Prefixes: h, human; r, rat; ara, Arabidopsis; t, Torpedo. Note that the mammalian ClCs fall into three subfamilies, and that all the higher plant ClCs are closely related to one another. Blue, prokaryotic; black, mammalian; pink, plant or fungal. The tree was constructed with the program Megalign (DNASTAR); the branch lengths are proportional to sequence distances.