Related Experiment Video
Updated: Jun 24, 2026
08:43
Simultaneous Measurement of Mitochondrial Calcium and Mitochondrial Membrane Potential in Live Cells by Fluorescent Microscopy
Published on: January 24, 2017
Calcium signalling: mitofusins promote interorganellar crosstalk
1Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford, UK. anant.parekh@dpag.ox.ac.uk
Current Biology : CB
|March 13, 2009
Summary
The endoplasmic reticulum and mitochondria tethering mechanism, crucial for calcium signaling, is elucidated. Dynamin-related mitofusins are identified as key proteins responsible for this vital organelle connection.
Area of Science:
- Cell Biology
- Mitochondrial Dynamics
- Calcium Signaling
Background:
- The endoplasmic reticulum (ER) and mitochondria are key organelles involved in cellular calcium (Ca2+) homeostasis.
- Physical tethering between the ER and mitochondria is known to facilitate Ca2+ transfer, but the molecular machinery remains elusive.
Purpose of the Study:
- To identify the molecular components responsible for tethering the ER and mitochondria.
- To understand the role of these tethers in facilitating Ca2+ signaling between organelles.
Main Methods:
- Investigated the role of dynamin-related proteins in organelle tethering.
- Utilized advanced microscopy and biochemical assays to analyze ER-mitochondria interactions.
Main Results:
- Identified mitofusins, a family of dynamin-related GTPases, as essential for ER-mitochondria tethering.
- Demonstrated that mitofusins mediate the physical connection, ensuring efficient Ca2+ flux.
Conclusions:
- Mitofusins play a fundamental role in establishing and maintaining ER-mitochondria contact sites.
- This tethering mechanism is critical for high-fidelity Ca2+ signaling, impacting various cellular processes.
Related Concept Videos
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
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,...
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,...
01:28The Inner Mitochondrial Membrane
The inner mitochondrial membrane is the primary site of ATP synthesis. The inner membrane domain that forms a smooth layer adjacent to the outer membrane is called the inner boundary membrane. This domain contains membrane transporters that drive metabolites in and out of the mitochondria. In contrast, the inner membrane network that invaginates into the matrix space is called the cristae membrane. This domain accounts for principle mitochondrial function as it accommodates the protein...
01:24Overview of Cell-Matrix Interactions
The extracellular matrix or ECM holds cells together to form a tissue and allows the cells within the tissue to communicate. ECM comprises proteins such as fibronectin, collagen, laminin, etc. The most abundant protein in this space is collagen. Collagen fibers are interwoven with carbohydrate-containing protein molecules called proteoglycans. ECM allows cell migration and provides a structural scaffold at cell adhesion that anchors the cell when the extracellular matrix proteins interact with...
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...