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Structural Analysis of Gel-Phase-Like Subdomains Formed in Lipid-Raft-Mimetic Bilayers
Masanao Kinoshita1,2, Mayu Maeda2, Nobuaki Matsumori2
1Division of Physics, Graduate School of Science and Technology, Gunma University, Aramaki 4-2, Maebashi, Gunma 371-8510, Japan.
Langmuir : the ACS Journal of Surfaces and Colloids
|June 23, 2026
Summary
This study reveals structural heterogeneity within lipid rafts, a key cell membrane component. Using low-flux electron diffraction, researchers found gel-phase-like subdomains composed of sphingomyelin within the ordered liquid phase.
Area of Science:
- Membrane Biophysics
- Cell Biology
- Structural Biology
Background:
- Lipid rafts are crucial ordered membrane domains involved in cell signaling.
- Previous studies suggested but could not confirm structural heterogeneity within lipid raft liquid-ordered (Lo) phases.
- Existing methods lacked the resolution to probe local membrane structures within lipid rafts.
Purpose of the Study:
- To investigate the local structural organization within lipid-raft-mimetic liquid-ordered (Lo) phases.
- To apply the low-flux electron diffraction (LFED) technique to lipid bilayers for the first time.
- To provide experimental evidence for structural heterogeneity within the Lo phase.
Main Methods:
- Development and application of a rapid-freezing and sublimation protocol for lipid bilayers.
- Optimization of electron beam flux for minimally invasive electron diffraction.
- Utilizing low-flux electron diffraction (LFED) to analyze local lipid chain packing in the Lo phase.
Main Results:
- Successfully prepared dehydrated lipid bilayers with preserved lipid chain packing.
- Observed sharp-ring and pseudohexagonal-spot diffractions within the Lo phase using LFED.
- These diffraction patterns matched those of pure sphingomyelin (SM) bilayers in the gel phase, indicating SM-rich subdomains.
Conclusions:
- The liquid-ordered (Lo) phase within lipid rafts contains subdomains with gel-phase-like lipid packing.
- These subdomains are likely composed of nearly pure sphingomyelin (SM).
- This finding provides new insights into the structural heterogeneity and functional versatility of lipid rafts.
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