Related Experiment Video
Updated: Dec 16, 2025

Imaging and Quantifying Mitochondrial Morphology in C. elegans During Aging
Published on: January 17, 2025
The ER chaperone calnexin controls mitochondrial positioning and respiration
Tomás Gutiérrez1, Hong Qi2, Megan C Yap1
1Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Abstract:
Chaperones in the endoplasmic reticulum (ER) control the flux of Ca2+ ions into mitochondria, thereby increasing or decreasing the energetic output of the oxidative phosphorylation pathway. An example is the abundant ER lectin calnexin, which interacts with sarco/endoplasmic reticulum Ca2+ ATPase (SERCA). We found that calnexin stimulated the ATPase activity of SERCA by maintaining its redox state. This function enabled calnexin to control how much ER Ca2+ was available for mitochondria, a key determinant for mitochondrial bioenergetics. Calnexin-deficient cells compensated for the loss of this function by partially shifting energy generation to the glycolytic pathway. These cells also showed closer apposition between the ER and mitochondria. Calnexin therefore controls the cellular energy balance between oxidative phosphorylation and glycolysis.
Related Concept Videos
Mitochondrial Protein Sorting
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
The Inner Mitochondrial Membrane
Protein Folding Quality Check in the RER
Mitochondrial Membranes
Energy to Drive Translocation
Generally, polypeptides are unfolded by two distinct...
Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...

