Cytoplasmic ATP-sensing domains regulate gating of skeletal muscle ClC-1 chloride channels
Date
2005
Authors
Bennetts, B.
Rychkov, G.
Ng, H.
Morton, C.
Stapleton, D.
Parker, M.
Cromer, B.
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Journal article
Citation
Journal of Biological Chemistry, 2005; 280(37):32452-32458
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Brett Bennetts, Grigori Y. Rychkov, Hooi-Ling Ng, Craig J. Morton, David Stapleton, Michael W. Parker, and Brett A. Cromer
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Abstract
ClC proteins are a family of chloride channels and transporters that are found in a wide variety of prokaryotic and eukaryotic cell types. The mammalian voltage-gated chloride channel ClC-1 is important for controlling the electrical excitability of skeletal muscle. Reduced excitability of muscle cells during metabolic stress can protect cells from metabolic exhaustion and is thought to be a major factor in fatigue. Here we identify a novel mechanism linking excitability to metabolic state by showing that ClC-1 channels are modulated by ATP. The high concentration of ATP in resting muscle effectively inhibits ClC-1 activity by shifting the voltage gating to more positive potentials. ADP and AMP had similar effects to ATP, but IMP had no effect, indicating that the inhibition of ClC-1 would only be relieved under anaerobic conditions such as intense muscle activity or ischemia, when depleted ATP accumulates as IMP. The resulting increase in ClC-1 activity under these conditions would reduce muscle excitability, thus contributing to fatigue. We show further that the modulation by ATP is mediated by cystathionine ß-synthase-related domains in the cytoplasmic C terminus of ClC-1. This defines a function for these domains as gating-modulatory domains sensitive to intracellular ligands, such as nucleotides, a function that is likely to be conserved in other ClC proteins.
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© 2005 by The American Society for Biochemistry and Molecular Biology, Inc.