Related Experiment Video

Updated: Aug 8, 2026

Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria
13:42

Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria

Published on: September 7, 2012

Newcomers in the process of mitochondrial permeabilization

Safa Lucken-Ardjomande1, Jean-Claude Martinou

  • 1Department of Cell Biology, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.

Journal of Cell Science
|January 28, 2005
PubMed

Insights

Cellular stress triggers apoptosis by releasing factors that permeabilize mitochondria. Pro-apoptotic proteins Bax and Bak are key, with their regulation involving both Bcl-2 family members and other proteins, alongside crucial mitochondrial lipid rearrangements.

Area of Science:

  • Cellular biology
  • Molecular biology
  • Biochemistry

Background:

  • Apoptosis, or programmed cell death, is a critical physiological process.
  • Mitochondrial outer membrane permeabilization (MOMP) is a key event in apoptosis, leading to the release of apoptogenic factors.
  • The Bcl-2 protein family, particularly Bax and Bak, plays a central role in regulating MOMP.

Purpose of the Study:

  • To elucidate the mechanisms underlying mitochondrial permeabilization during apoptosis.
  • To investigate the roles of both Bcl-2 family proteins and other unrelated proteins in regulating Bax and Bak.
  • To explore the contribution of mitochondrial lipid rearrangements to the MOMP process.

Main Methods:

  • The study likely involves biochemical assays to study protein-protein interactions and protein activity.
  • Cellular assays to monitor apoptosis and mitochondrial integrity.
  • Lipidomic analyses to investigate changes in mitochondrial lipid composition during apoptosis.

Main Results:

  • Activation of pro-apoptotic proteins Bax and Bak is essential for MOMP.
  • Regulation of Bax and Bak involves not only Bcl-2 family members but also other proteins acting as inhibitors or activators.
  • Significant rearrangements in mitochondrial lipids occur during apoptosis and are integral to the permeabilization process.

Conclusions:

  • Mitochondrial permeabilization during apoptosis is a complex process regulated by multiple factors.
  • The interplay between Bcl-2 family proteins, other regulatory proteins, and mitochondrial lipids is crucial for controlling cell death.
  • Mitochondrial lipids play a more significant role in MOMP than previously understood.

More Related Videos

Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells08:29

Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells

Published on: April 27, 2018

Assessment of Open Probability of the Mitochondrial Permeability Transition Pore in the Setting of Coenzyme Q Excess07:35

Assessment of Open Probability of the Mitochondrial Permeability Transition Pore in the Setting of Coenzyme Q Excess

Published on: June 1, 2022

Related Concept Videos

Mitochondrial Protein Sorting01:39

Mitochondrial Protein Sorting

Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Mitochondrial Precursor Proteins01:39

Mitochondrial Precursor Proteins

Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70  chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial precursors...
Translocation of Proteins into the Mitochondria01:19

Translocation 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,...
Energy to Drive Translocation01:37

Energy to Drive Translocation

Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
Porin Insertion in the Outer Mitochondrial Membrane01:12

Porin Insertion in the Outer Mitochondrial Membrane

Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Protein Transport into the Inner Mitochondrial Membrane01:34

Protein Transport into the Inner Mitochondrial Membrane

Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...