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Biophys J. 2002 Jan;82(1 Pt 1):509-16.

A genetically targetable fluorescent probe of channel gating with rapid kinetics.

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The John B. Pierce Laboratory, Interdepartmental Neuroscience Program, Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06519, USA.


We have developed a genetically targetable, optical channel-gating reporter that converts rapid membrane potential changes into changes in fluorescence intensity. We have named this construct SPARC (sodium channel protein-based activity reporting construct). Green fluorescent protein was inserted into an intracellular loop of a reversibly nonconducting form of the rat mu I skeletal muscle voltage-gated sodium channel. Rapid changes of the membrane potential modulate the fluorescence of the inserted green fluorescent protein. This change in fluorescence can faithfully report depolarizing pulses as short as 2 ms. The fluorescence signal does not inactivate during extended depolarizations. Several features of the probe's response properties indicate that it likely reports gating charge movement of a single domain of rat mu I skeletal muscle. This probe provides a new approach for studying rapid channel movements and may possibly act as a fluorescent activity reporter in excitable cells.

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