title: A monomer is the minimum functional unit required for channel and ATPase activity of the cystic fibrosis transmembrane conductance regulator.
abstract: The cystic fibrosis transmembrane conductance regulator (CFTR) normally functions as a phosphorylation-regulated chloride channel on the apical surface of epithelial cells, and lack of this function is the primary cause for the fatal disease cystic fibrosis (CF). Previous studies showed that purified, reconstituted CFTR can function as a chloride channel and, further, that its intrinsic ATPase activity is required to regulate opening and closing of the channel gate. However, these previous studies did not identify the quaternary structure required to mediate conduction and catalysis. Our present studies show that CFTR molecules may self-associate in CHO and Sf9 membranes, as complexes close to the predicted size of CFTR dimers can be captured by chemical cross-linking reagents and detected using nondissociative PAGE. However, CFTR function does not require a multimeric complex for function as we determined that purified, reconstituted CFTR monomers are sufficient to mediate regulated chloride conduction and ATPase activity.
authors.affiliation: Research Institute, Hospital for Sick Children, Ontario M5G 1X8, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Ramjeesingh
authors.forename: C
authors.initials: C
authors.lastname: Li
authors.forename: I
authors.initials: I
authors.lastname: Kogan
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: L J
authors.initials: LJ
authors.lastname: Huan
authors.forename: C E
authors.initials: CE
authors.lastname: Bear
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018118:Chloride Channels / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D003432:Cross-Linking Reagents; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D004789:Enzyme Activation; D008051:Lipid Bilayers; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D020836:Protein Structure, Quaternary
chemical_list: D018118:Chloride Channels; D003432:Cross-Linking Reagents; D008051:Lipid Bilayers; D008565:Membrane Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000251:Adenosine Triphosphatases