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Updated: Jun 26, 2026
06:26
Pulling Membrane Nanotubes from Giant Unilamellar Vesicles
Published on: December 7, 2017
Asymmetric phase transitions in lipid bilayers: coupling or bending?
Mona Krompers1, Miriam Jaki1, Sinja Götz1
1Department of Pharmaceutics, University of Freiburg, Institute of Pharmaceutical Sciences, Freiburg, Germany. heiko.heerklotz@pharmazie.uni-freiburg.de.
Faraday Discussions
|May 6, 2025
Summary
Lipid-asymmetric large unilamellar vesicles (aLUVs) exhibit interleaflet coupling and vesicle budding, influenced by preparation temperature. These phenomena are alternative responses to asymmetric membrane expansion, impacting biomembrane behavior.
Area of Science:
- Biophysics
- Membrane Biophysics
- Lipid Bilayer Dynamics
Background:
- Biomembranes possess asymmetric lipid compositions in their leaflets.
- Interleaflet coupling, where ordered domains in one leaflet affect the other, is crucial for transmembrane signaling.
- Lipid phase transitions and resulting area mismatches can induce membrane stress, potentially leading to coupling or budding.
Purpose of the Study:
- To investigate the relationship between lipid asymmetry, membrane stress, and the resulting phenomena of interleaflet coupling and vesicle budding.
- To explore how preparation temperature influences the behavior of lipid-asymmetric large unilamellar vesicles (aLUVs).
Main Methods:
- Preparation of lipid-asymmetric large unilamellar vesicles (aLUVs) with distinct lipid compositions in inner and outer leaflets.
- Pressure perturbation calorimetry to record phase transitions in aLUVs and large unilamellar vesicles (LUVs).
- Asymmetric flow field-flow fractionation (AF4) for monitoring vesicle budding, cryo-transmission electron microscopy for visualization, HPLC for lipid quantification, and zeta potential for outer-leaflet lipid detection.
Main Results:
- aLUVs were successfully prepared at 5, 15, and 30 °C, with varying degrees of gel phase in the outer leaflet.
- aLUVs prepared at lower temperatures (5 and 15 °C) exhibited exovesicle budding upon heating and weak interleaflet coupling.
- aLUVs prepared at 30 °C (both leaflets fluid) showed stronger interleaflet coupling during asymmetric freezing/melting.
Conclusions:
- Vesicle budding and interleaflet coupling act as alternative mechanisms for accommodating asymmetric membrane expansion stress.
- Preparation temperature significantly influences the balance between budding and coupling in lipid-asymmetric vesicles.
- Understanding and predicting interleaflet coupling in aLUV systems remains a critical open question in membrane biophysics.
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