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Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue
Published on: March 23, 2015
Annexin V binding perturbs the cardiolipin fluidity gradient in isolated mitochondria. Can it affect mitochondrial
F M Megli1, M Mattiazzi, T Di Tullio
1Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, V. Orabona, 4, 70126 Bari, Italy.
Biochemistry
|May 23, 2000
Summary
Annexin V binding to mitochondrial membranes rigidifies the bilayer, particularly affecting cardiolipin. This localized fluidity change may impact mitochondrial function.
Area of Science:
- Biochemistry
- Biophysics
- Cell Biology
Background:
- Annexin V is a calcium-dependent phospholipid-binding protein.
- Mitochondrial membranes contain distinct phospholipid domains, including cardiolipin pools.
- Understanding protein-lipid interactions is crucial for mitochondrial function.
Purpose of the Study:
- To investigate the effect of annexin V binding on the fluidity of mitochondrial and artificial phospholipid membranes.
- To determine how annexin V affects different phospholipid species, especially cardiolipin.
- To explore potential implications for mitochondrial functionality.
Main Methods:
- Electron Paramagnetic Resonance (EPR) spectroscopy was used to probe membrane fluidity.
- Phospholipid spin labels (cardiolipin, phosphatidylcholine, phosphatidylethanolamine) were used at various acyl chain positions.
- Computer-aided spectral titration and temperature calibration were employed to quantify changes.
Main Results:
- Annexin V binding induced membrane rigidity, primarily affecting the inner bilayer up to acyl position C-12.
- In isolated mitochondria, cardiolipin was more affected by annexin V than other phospholipids.
- In vesicles from mitochondrial phospholipids, all species were affected similarly, suggesting specific mitochondrial cardiolipin domains.
Conclusions:
- Annexin V binding alters mitochondrial membrane fluidity, with a pronounced effect on cardiolipin.
- The distinct behavior of cardiolipin in mitochondrial membranes supports the hypothesis of specific annexin V binding sites.
- The observed fluidity alterations raise questions about annexin V's potential influence on mitochondrial functionality in vitro.
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