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Regulation of CFTR channel gating
D C Gadsby1, T C Hwang, T Baukrowitz
1Laboratory of Cardiac/Membrane Physiology, Rockefeller University, New York, NY 10021, USA.
The Japanese Journal of Physiology
|January 1, 1994
Summary
Cystic fibrosis transmembrane conductance regulator (CFTR) channel gating is complex, involving incremental protein kinase A (PKA) phosphorylation. This differential phosphorylation controls two distinct nucleotide-binding domains (NBDs) for channel opening and closing.
Area of Science:
- Molecular biology
- Cellular physiology
- Ion channel function
Background:
- Cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel crucial for epithelial function.
- Dysregulation of CFTR ion channel activity is implicated in cystic fibrosis.
- Understanding CFTR gating mechanisms is essential for therapeutic development.
Purpose of the Study:
- To elucidate the complex regulatory model of CFTR chloride channel gating.
- To investigate the role of protein kinase A (PKA) phosphorylation in CFTR function.
- To differentiate the functional roles of CFTR's two nucleotide-binding domains (NBDs).
Main Methods:
- Utilized biochemical assays to study CFTR phosphorylation.
- Employed non-hydrolyzable ATP analogues (AMP-PNP) to probe nucleotide-binding domains.
- Investigated responses to inorganic phosphate analogues (orthovanadate) to infer ATP hydrolysis.
Main Results:
- CFTR regulation involves incremental PKA phosphorylation at multiple sites.
- The two NBDs of CFTR are functionally distinct in their response to nucleotides.
- Evidence suggests ATP hydrolysis occurs at both NBDs, initiating both channel opening and closing.
Conclusions:
- A complex model for CFTR gating is supported, involving differential PKA phosphorylation.
- Functional asymmetry of NBDs is critical for CFTR channel activity.
- ATP hydrolysis at both NBDs is proposed to regulate the open-closed state of the CFTR channel.