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Bending Stiffness Depends on Curvature of Ternary Lipid Mixture Tubular Membranes
- Publication Year :
- 2009
- Publisher :
- The Biophysical Society, 2009.
-
Abstract
- Lipid and protein sorting and trafficking in intracellular pathways maintain cellular function and contribute to organelle homeostasis. Biophysical aspects of membrane shape coupled to sorting have recently received increasing attention. Here we determine membrane tube bending stiffness through measurements of tube radii, and demonstrate that the stiffness of ternary lipid mixtures depends on membrane curvature for a large range of lipid compositions. This observation indicates amplification by curvature of cooperative lipid demixing. We show that curvature-induced demixing increases upon approaching the critical region of a ternary lipid mixture, with qualitative differences along two roughly orthogonal compositional trajectories. Adapting a thermodynamic theory earlier developed by M. Kozlov, we derive an expression that shows the renormalized bending stiffness of an amphiphile mixture membrane tube in contact with a flat reservoir to be a quadratic function of curvature. In this analytical model, the degree of sorting is determined by the ratio of two thermodynamic derivatives. These derivatives are individually interpreted as a driving force and a resistance to curvature sorting. We experimentally show this ratio to vary with composition, and compare the model to sorting by spontaneous curvature. Our results are likely to be relevant to the molecular sorting of membrane components in vivo.
- Subjects :
- Lipid Bilayers
Analytical chemistry
Biophysics
Thermodynamics
Complex Mixtures
Curvature
01 natural sciences
Quantitative Biology::Cell Behavior
Quantitative Biology::Subcellular Processes
03 medical and health sciences
0103 physical sciences
010306 general physics
Lipid bilayer
030304 developmental biology
0303 health sciences
Physics::Biological Physics
Chemistry
Cell Membrane
Membrane
Lipids
Biomechanical Phenomena
Tube bending
Membrane curvature
Bending stiffness
Linear Models
Emulsions
Ternary operation
Membrane biophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....298bfff595478546338ed4e0855286d2