CFTR, a channel with the structure of a transporter.

The cystic fibrosis transmembrane conductance regulator (CFTR) belongs to a superfamily of active transport molecules. However, when expressed in a wide variety of heterologous cell systems and when purified to homogeneity and reconstituted in planar lipid bilayers, it exhibits low conductance chloride channel activity. We postulate that the active transport capability of the molecule has been adapted to provide very stringent metabolic control of this channel which is responsible for chloride secretion and hydration of wet epithelial surfaces.