Related Experiment Video

Updated: Jul 7, 2026

Inner Mitochondrial Membrane Sensitivity to Na+ Reveals Partially Segmented Functional CoQ Pools
05:27

Inner Mitochondrial Membrane Sensitivity to Na+ Reveals Partially Segmented Functional CoQ Pools

Published on: July 20, 2022

Phosphate transport in mitochondria and submitochondrial particles: the influence of thiol oxidation

F Zoccarato1, M Rugolo, D Siliprandi

  • 1Institute of Biological Chemistry, University of Padova.

Journal of Bioenergetics and Biomembranes
|June 1, 1977
PubMed

Insights

Diamide, a thiol oxidizing agent, partially inhibits phosphate (Pi) uptake in rat liver mitochondria. This inhibition is temperature-dependent, suggesting specific thiol group involvement in mitochondrial Pi transport.

Area of Science:

  • Biochemistry
  • Mitochondrial Physiology
  • Membrane Transport

Background:

  • Mitochondria are crucial for cellular energy production.
  • Phosphate (Pi) transport across the inner mitochondrial membrane is vital for ATP synthesis.
  • The precise mechanisms and orientation of Pi transporters are not fully understood.

Purpose of the Study:

  • To investigate the role of thiol groups in mitochondrial phosphate (Pi) transport.
  • To compare the sensitivity of Pi transport in liver and heart mitochondria to thiol modification.
  • To explore the asymmetric orientation of the Pi transport system.

Main Methods:

  • Utilizing diamide, a thiol oxidizing agent, to probe mitochondrial thiol groups.
  • Measuring Pi uptake and efflux in isolated rat liver and heart mitochondria.
  • Employing submitochondrial vesicles to assess Pi transport under different conditions.
  • Quantifying mitochondrial thiol groups titrated by diamide.

Main Results:

  • Diamide partially inhibited Pi uptake in rat liver mitochondria in a temperature-dependent manner.
  • Optimal inhibition occurred at 20°C, reducing the mersalyl requirement for Pi transport inhibition.
  • Pi efflux was unaffected by diamide, and heart mitochondria showed insensitivity to diamide inhibition.
  • Diamide inhibited Pi accumulation in submitochondrial heart vesicles, indicating differential thiol accessibility.

Conclusions:

  • Mitochondrial Pi transport involves specific thiol groups whose accessibility differs between liver and heart mitochondria.
  • The results support an asymmetric orientation of the Pi transport system within the mitochondrial membrane.
  • Thiol group accessibility provides insights into the distinct functional characteristics of mitochondria from various sources.

More Related Videos

F1FO ATPase Vesicle Preparation and Technique for Performing Patch Clamp Recordings of Submitochondrial Vesicle Membranes08:21

F1FO ATPase Vesicle Preparation and Technique for Performing Patch Clamp Recordings of Submitochondrial Vesicle Membranes

Published on: May 4, 2013

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

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,...
ATP Synthase: Mechanism01:48

ATP Synthase: Mechanism

In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...
The Electron Transport Chain01:30

The Electron Transport Chain

The electron transport chain or oxidative phosphorylation is an exothermic process in which free energy released during electron transfer reactions is coupled to ATP synthesis. This process is a significant source of energy in aerobic cells, and therefore inhibitors of the electron transport chain can be detrimental to the cell's metabolic processes.
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q in...
Pyruvate Oxidation01:15

Pyruvate Oxidation

After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure that pyruvate can enter the next metabolic pathway so that energy stored in the pyruvate molecules can be harnessed by the cells.
First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
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...
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...