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Updated: Jun 25, 2025
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Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells
Published on: April 27, 2018
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KRAP regulates mitochondrial Ca2+ uptake by licensing IP3 receptor activity and stabilizing ER-mitochondrial
Peace Atakpa-Adaji1, Adelina Ivanova1, Karolina Kujawa1
1Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.
Journal of Cell Science
|May 24, 2024
Summary
Kras-induced actin-interacting protein (KRAP) licenses inositol 1,4,5-trisphosphate receptors (IP3Rs) to release calcium to mitochondria. KRAP also stabilizes ER-mitochondrial contact sites, regulating calcium transfer.
Area of Science:
- Cell Biology
- Molecular Biology
- Calcium Signaling
Background:
- Inositol 1,4,5-trisphosphate receptors (IP3Rs) mediate calcium (Ca2+) release from the endoplasmic reticulum (ER) to the cytosol and other organelles at membrane contact sites (MCSs).
- A subset of IP3Rs are 'licensed' by Kras-induced actin-interacting protein (KRAP) to release Ca2+ into the cytosol, primarily near the plasma membrane.
Purpose of the Study:
- To investigate whether KRAP regulates IP3R activity at ER-mitochondrial membrane contact sites (ERMCSs).
- To determine KRAP's role in Ca2+ transfer from IP3Rs to mitochondria.
Main Methods:
- Simultaneous measurement of cytosolic and mitochondrial matrix Ca2+ concentrations.
- Proximity ligation assay to assess interactions between IP3R and voltage-dependent anion channel 1 (VDAC1).
Main Results:
- KRAP licenses IP3Rs to release Ca2+ to both the cytosol and mitochondria.
- Loss of KRAP abolished Ca2+ signals evoked by IP3R stimulation.
- KRAP is localized at ERMCSs containing IP3R clusters.
- KRAP deficiency reduced the number of ERMCSs.
Conclusions:
- KRAP plays a dual role in regulating Ca2+ transfer to mitochondria.
- KRAP licenses IP3R activity and stabilizes ERMCSs, thereby controlling Ca2+ flux to mitochondria.
Keywords:
Ca2+Endoplasmic reticulumHeLa cellHistamineIP3 receptorKRAPMCUMembrane contact siteMitochondriaProximity ligation assayVDAC1More Related Videos
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