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Budding and fission of vesicles
H G Döbereiner1, J Käs, D Noppl
1Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada.
Biophysical Journal
|October 1, 1993
Summary
Protein-free vesicles undergo budding and fission, essential cellular processes, driven by lipid bilayer physics and composition, not requiring coat proteins. This reveals intrinsic membrane dynamics.
Area of Science:
- Biophysics
- Cell Biology
- Materials Science
Background:
- Vesicle budding and fission are critical for cellular transport.
- These processes are traditionally thought to require coat proteins.
Purpose of the Study:
- To investigate if protein-free lipid vesicles can undergo budding and fission.
- To identify the physical mechanisms driving these shape transitions in lipid bilayers.
Main Methods:
- Studied natural lipid mixtures (bovine brain sphingomyelins) and synthetic mixtures (DMPC/cholesterol).
- Induced budding via heating to alter area-to-volume ratio.
- Monitored morphology with phase contrast microscopy.
- Analyzed thermal behavior using differential scanning calorimetry.
- Examined vesicle structure with freeze fracture electron microscopy.
Main Results:
- Demonstrated budding and fission in protein-free lipid vesicles.
- Observed these processes occur at biologically relevant length scales.
- Identified liquid/gel domain formation and spontaneous curvature coupling as driving forces.
- Showcased osmotic induction of budding and fission in lipid-cholesterol mixtures.
Conclusions:
- Coat proteins are not essential for vesicle budding and fission.
- The inherent physics of lipid bilayers can account for these membrane dynamics.
- Findings challenge the necessity of proteins for fundamental vesicle formation and scission events.