Journal article
5'-Adenylylimidodiphosphate does not activate CFTR chloride channels in cell-free patches of membrane
American journal of physiology. Lung cellular and molecular physiology, Vol.265(1), pp.L27-L32
07/01/1993
DOI: 10.1152/ajplung.1993.265.1.L27
PMID: 7687826
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel requires both phosphorylation of its R domain and the presence of nucleoside triphosphates for activation. Our previous work suggested that hydrolysis of nucleoside triphosphates may be required to support channel activity. However, recent studies have suggested that the nonhydrolyzable adenosine triphosphate analogue, 5'-adenylylimidodiphosphate (AMP-PNP), may support some Cl- channel activity in sweat gland duct epithelia in the presence of low ATP concentration and in Cl- channels associated with expression of the P-glycoprotein multidrug resistance transporter. To examine the effect of AMP-PNP, we applied it to the cytosolic surface of phosphorylated CFTR Cl- channels contained in excised, cell-free patches of membrane. We found that preparations of 10 mM AMP-PNP opened phosphorylated CFTR Cl- channels. However, this effect was due to contaminating ATP: high-pressure liquid chromatography analysis of AMP-PNP demonstrated that 10 mM AMP-PNP could contain up to 50 microM ATP, which could account for the observed stimulation of CFTR Cl- channel activity. When contaminating ATP was hydrolyzed with hexokinase, AMP-PNP was unable to support CFTR channel activity. AMP-PNP (10 mM) also failed to attenuate or potentiate the current induced by 0.3 mM ATP. These results suggest that AMP-PNP has no direct effect on CFTR Cl- channels.
Details
- Title: Subtitle
- 5'-Adenylylimidodiphosphate does not activate CFTR chloride channels in cell-free patches of membrane
- Creators
- Mark R Carson - Howard Hughes Medical Institute, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242Michael J. Welsh - Howard Hughes Medical Institute, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242
- Resource Type
- Journal article
- Publication Details
- American journal of physiology. Lung cellular and molecular physiology, Vol.265(1), pp.L27-L32
- DOI
- 10.1152/ajplung.1993.265.1.L27
- PMID
- 7687826
- NLM abbreviation
- Am J Physiol Lung Cell Mol Physiol
- ISSN
- 1040-0605
- eISSN
- 1522-1504
- Publisher
- American Physiological Society
- Language
- English
- Date published
- 07/01/1993
- Academic Unit
- Neurology; Molecular Physiology and Biophysics; Neurosurgery; Internal Medicine
- Record Identifier
- 9984020703002771
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