A quantitative model describing the selective solubilization of membrane domains
Sandro Keller1, Alekos Tsamaloukas, Heiko Heerklotz
1Research Institute of Molecular Pharmacology FMP, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
Journal of the American Chemical Society
|August 11, 2005
Summary
A new thermodynamic model explains detergent-resistant membranes (DRMs). It shows ordered lipid domains resist solubilization, with cholesterol potentially crucial for forming isolatable DRM fragments.
Area of Science:
- Biophysics
- Membrane Biology
- Thermodynamics
Background:
- Classical membrane solubilization models fail for domain-forming membranes.
- Detergent-resistant membranes (DRMs) lack a quantitative thermodynamic model.
- Existing assumptions consider ordered domains inert and fluid domains solubilized.
Purpose of the Study:
- To establish a quantitative thermodynamic model for detergent-resistant membrane (DRM) formation.
- To describe the behavior of demixed, domain-forming membranes during solubilization.
- To investigate the role of lipid composition and cholesterol in DRM formation.
Main Methods:
- Developed a quantitative equilibrium thermodynamics model.
- The model includes two lipids and one detergent across four phases.
- Calculated phase boundaries and component concentrations.
Main Results:
- The model predicts significant variation in ordered domain abundance and composition during detergent addition.
- Thermodynamic resistance of ordered lipid domains is independent of the fluid phase.
- Cholesterol may be essential for increasing the size of resistant fragments and enhancing domain formation.
Conclusions:
- The classical three-stage model is inadequate for domain-forming membranes and DRMs.
- A new thermodynamic framework accurately models DRM formation.
- Cholesterol plays a critical role in the formation and isolation of DRMs.
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