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Updated: May 12, 2026

Fluorescence-based Measurement of Store-operated Calcium Entry in Live Cells: from Cultured Cancer Cell to Skeletal Muscle Fiber
Published on: February 13, 2012
The skeletal muscle calcium release channel: coupled O2 sensor and NO signaling functions
1Howard Hughes Medical Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
Abstract:
Ion channels have been studied extensively in ambient O2 tension (pO2), whereas tissue PO2 is much lower. The skeletal muscle calcium release channel/ryanodine receptor (RyR1) is one prominent example. Here we report that PO2 dynamically controls the redox state of 6-8 out of 50 thiols in each RyR1 subunit and thereby tunes the response to NO. At physiological pO2, nanomolar NO activates the channel by S-nitrosylating a single cysteine residue. Among sarcoplasmic reticulum proteins, S-nitrosylation is specific to RyR1 and its effect on the channel is calmodulin dependent. Neither activation nor S-nitrosylation of the channel occurs at ambient PO2. The demonstration that channel cysteine residues subserve coupled O2 sensor and NO regulatory functions and that these operate through the prototypic allosteric effector calmodulin may have general implications for the regulation of redox-related systems.
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