Commentary Cystic Fibrosis Transmembrane Conductance Regulator : Permeant Ions Find the Pore

In the 8 yr since the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) was identified by means of positional cloning (Kerem et al., 1989; Riordan et al., 1989; Rommens et al., 1989), the Cl channel function of CFTR has been studied in a wide variety of expression systems. Macroscopic and single-channel currents have been measured and a large number of mutant constructs containing either single amino acid substitutions or major deletions have been examined. It is ironic, however, that despite this intense activity, there is little available in the published literature in the way of a systematic characterization of the conduction properties of this unique Cl channel. In this issue of The Journal of General Physiology, John Hanrahan and his colleagues make an important contribution to this question in the form of three papers in which they report experimental and modeling results...