Regulation by ATP and ADP of CFTR chloride channels that contain mutant nucleotide-binding domains.
Regulation of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is unusual in that phosphorylated channels require cytosolic adenosine triphosphate (ATP) to open. The CFTR contains two regions predicted to be nucleotide-binding domains (NBDs); site-directed mutations in each NBD have now been shown to alter the relation between ATP concentration and channel activity, which indicates that ATP stimulates the channel by direct interaction with both NBDs. The two NBDs are not, however, functionally equivalent: adenosine diphosphate (ADP) competitively inhibited the channel by interacting with NBD2 but not by interacting with NBD1. Four cystic fibrosis-associated mutations in the NBDs reduced absolute chloride channel activity, and one mutation also decreased the potency with which ATP stimulates channel activity. Dysfunction of ATP-dependent stimulation through the NBDs may be the basis for defective CFTR chloride channel activity in some cystic fibrosis patients.
Anderson
M P
MP
Howard Hughes Medical Institute, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Welsh
M J
MJ
D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D002460:Cell Line; D018118:Chloride Channels; D000242:Cyclic AMP / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009711:Nucleotides / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism
D018118:Chloride Channels; D008565:Membrane Proteins; D009711:Nucleotides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011494:Protein Kinases