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Updated: Dec 23, 2025

Assembly and Characterization of Biomolecular Memristors Consisting of Ion Channel-doped Lipid Membranes
Published on: March 9, 2019
Variable Assembly of EMRE and MCU Creates Functional Channels with Distinct Gatekeeping Profiles
Riley Payne1, Carmen Li1, J Kevin Foskett2
1Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Most mitochondrial calcium channels (MCU) function with two EMRE subunits, not four, regulating calcium influx. Varying EMRE levels fine-tune channel activity and gatekeeping in cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Physiology
Background:
- Mitochondrial calcium uniporter (MCU) channels regulate cellular calcium homeostasis.
- The MCU complex includes pore-forming MCU, regulatory MICU1/2, and essential EMRE subunits.
- The in vivo stoichiometry of MCU and EMRE remains undetermined.
Purpose of the Study:
- To investigate the in vivo stoichiometry of the MCU-EMRE complex.
- To determine how EMRE stoichiometry affects MCU channel activity and gatekeeping.
- To elucidate the functional consequences of varying EMRE:MCU ratios.
Main Methods:
- Expression of tagged MCU and EMRE subunits in EMRE/MCU-deficient cells.
- Utilizing MCU-EMRE concatemers to enforce specific stoichiometries (1:4, 4:4, 2:4).
- Assessing Ca2+ uptake and gatekeeping by measuring cytoplasmic Ca2+ concentration ([Ca2+]).
Main Results:
- A 1:10 EMRE:MCU ratio partially restored channel activity but not full gatekeeping.
- Increased EMRE expression elevated the Ca2+ threshold for MCU channel activation.
- Concatemers with 2EMRE:4MCU stoichiometry mimicked endogenous MCU channel activity and gatekeeping.
- Complexes with 1-4 EMRE subunits exhibited varying degrees of activity and gatekeeping.
Conclusions:
- Mitochondrial calcium channels do not require four EMRE subunits for function.
- Most endogenous MCU channels likely contain two EMRE subunits.
- The stoichiometry of EMRE within the MCU complex is critical for precise calcium regulation.
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