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Acyl chain length and saturation modulate interleaflet coupling in asymmetric bilayers: effects on dynamics and
Salvatore Chiantia1, Erwin London
1Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY, USA. chiantia@gmail.com
Biophysical Journal
|January 4, 2013
Summary
Membrane leaflet coupling varies. Sphingomyelin in the outer leaflet strongly coupled lateral diffusion in the inner leaflet, but did not affect membrane order between leaflets.
Area of Science:
- Biophysics
- Membrane Biology
- Lipid Bilayer Dynamics
Background:
- The physical properties of lipid bilayers are crucial for membrane function.
- Understanding the coupling between inner and outer leaflets is key to membrane structure-function relationships.
Purpose of the Study:
- To investigate the coupling of physical properties between the inner and outer leaflets of lipid bilayers.
- To determine how acyl chain structure influences leaflet coupling.
Main Methods:
- Preparation of asymmetric vesicles with phosphatidylcholine (PC) in the inner leaflet and sphingomyelin (SM) in the outer leaflet.
- Monitoring lateral diffusion and membrane order as a function of lipid acyl chain composition.
Main Results:
- Outer leaflet sphingomyelin strongly coupled lateral diffusion in the inner leaflet, especially with specific acyl chain structures.
- Introduction of long acyl chain sphingomyelin significantly reduced inner leaflet diffusion, indicating strong coupling.
- No detectable coupling was observed between inner and outer leaflet membrane order, despite changes in outer leaflet order.
Conclusions:
- Lateral diffusion is strongly coupled between lipid bilayer leaflets depending on acyl chain structure.
- Membrane order is not detectably coupled between leaflets.
- A model for coupled lateral diffusion is proposed, with implications for membrane function.
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