title: Identification and regulation of the cystic fibrosis transmembrane conductance regulator-generated chloride channel.
abstract: Cystic fibrosis transmembrane conductance regulator (CFTR) generates cAMP-regulated Cl- channels; mutations in CFTR cause defective Cl- channel function in cystic fibrosis epithelia. We used the patch-clamp technique to determine the single channel properties of Cl- channels in cell expressing recombinant CFTR. In cell-attached patches, an increase in cellular cAMP reversibly activated low conductance Cl- channels. cAMP-dependent regulation is due to phosphorylation, because the catalytic subunit of cAMP-dependent protein kinase plus ATP reversibly activated the channel in excised, cell-free patches of membrane. In symmetrical Cl- solutions, the channel had a channel conductance of 10.4 +/- 0.2 (n = 7) pS and a linear current-voltage relation. The channel was more permeable to Cl- than to I- and showed no appreciable time-dependent voltage effects. These biophysical properties are consistent with macroscopic studies of Cl- channels in single cells expressing CFTR and in the apical membrane of secretory epithelia. Identification of the single channel characteristics of CFTR-generated channels allows further studies of their regulation and the mechanism of ion permeation.
authors.affiliation: Howard Hughes Medical Institute, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
authors.forename: H A
authors.initials: HA
authors.lastname: Berger
authors.forename: M P
authors.initials: MP
authors.lastname: Anderson
authors.forename: R J
authors.initials: RJ
authors.lastname: Gregory
authors.forename: S
authors.initials: S
authors.lastname: Thompson
authors.forename: P W
authors.initials: PW
authors.lastname: Howard
authors.forename: R A
authors.initials: RA
authors.lastname: Maurer
authors.forename: R
authors.initials: R
authors.lastname: Mulligan
authors.forename: A E
authors.initials: AE
authors.lastname: Smith
authors.forename: M J
authors.initials: MJ
authors.lastname: Welsh
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D018118:Chloride Channels; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D011494:Protein Kinases / Q000494:pharmacology
chemical_list: C505032:CFTR protein, human; D018118:Chloride Channels; D008565:Membrane Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000255:Adenosine Triphosphate; D011494:Protein Kinases