CFTR is an important protein that, when mutated, causes the life-threatening genetic disease cystic fibrosis. A study in The Journal of General Physiology (JGP) details how an accidental discovery has provided new understanding about CFTR functionality. From a scientific standpoint, CFTR is unique in that it is the only known ion channel—a protein pore that enables the passive diffusion of ions across cell membranes—in the enormous superfamily of ABC proteins, which normally operate as active transporters. As active transporters, ABC proteins use energy derived from ATP hydrolysis to move substrates across the cell membrane against a concentration gradient. Although CFTR is equipped with the same structural elements as that of its ABC family “brethren,” it has been unclear whether the ion channel also functions in the same way.
