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Updated: Aug 30, 2026

Monitoring Dynamic Changes In Mitochondrial Calcium Levels During Apoptosis Using A Genetically Encoded Calcium Sensor
Published on: April 1, 2011
Cytochrome c binds to inositol (1,4,5) trisphosphate receptors, amplifying calcium-dependent apoptosis
Darren Boehning1, Randen L Patterson, Leela Sedaghat
1Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, Maryland 21205, USA.
Abstract:
Mitochondrial cytochrome c release and inositol (1,4,5) trisphosphate receptor (InsP(3)R)-mediated calcium release from the endoplasmic reticulum mediate apoptosis in response to specific stimuli. Here we show that cytochrome c binds to the InsP(3)R during apoptosis. Addition of 1 nM cytochrome c blocks calcium-dependent inhibition of InsP(3)R function. Early in apoptosis, cytochrome c translocates to the endoplasmic reticulum where it selectively binds InsP(3)R, resulting in sustained, oscillatory cytosolic calcium increases. These calcium events are linked to the coordinate release of cytochrome c from all mitochondria. Our findings identify a feed-forward mechanism whereby early cytochrome c release increases InsP(3)R function, resulting in augmented cytochrome c release that amplifies the apoptotic signal.
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