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Updated: Aug 10, 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
Energized mitochondria increase the dynamic range over which inositol 1,4,5-trisphosphate activates store-operated
J A Gilabert1, D Bakowski, A B Parekh
1Laboratory of Molecular and Cellular Signalling, Department of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
Abstract:
In eukaryotic cells, activation of cell surface receptors that couple to the phosphoinositide pathway evokes a biphasic increase in intracellular free Ca2+ concentration: an initial transient phase reflecting Ca2+ release from intracellular stores, followed by a plateau phase due to Ca2+ influx. A major component of this Ca2+ influx is store-dependent and often can be measured directly as the Ca2+ release-activated Ca2+ current (I(CRAC)). Under physiological conditions of weak intracellular Ca2+ buffering, respiring mitochondria play a central role in store-operated Ca2+ influx. They determine whether macroscopic I(CRAC) activates or not, to what extent and for how long. Here we describe an additional role for energized mitochondria: they reduce the amount of inositol 1,4,5-trisphosphate (InsP3) that is required to activate I(CRAC). By increasing the sensitivity of store-operated influx to InsP3, respiring mitochondria will determine whether modest levels of stimulation are capable of evoking Ca2+ entry or not. Mitochondrial Ca2+ buffering therefore increases the dynamic range of concentrations over which the InsP3 is able to function as the physiological messenger that triggers the activation of store-operated Ca2+ influx.
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