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Passive or active fluctuations in membranes containing proteins
P Girard1, J Prost, P Bassereau
1PhysicoChimie Curie, UMR CNRS-Institut Curie 168, 11 rue Pierre et Marie Curie, 75231 Paris CEDEX 05, France.
Physical Review Letters
|March 24, 2005
Summary
The Ca2+-ATPase protein significantly alters giant vesicle membrane properties, affecting their shape fluctuations. Researchers quantified active forces generated by this protein upon ATP activation.
Area of Science:
- Biophysics
- Membrane Protein Dynamics
- Cellular Mechanics
Background:
- Giant vesicles are model systems for studying cell membrane properties.
- Transmembrane proteins play crucial roles in modulating membrane behavior.
- Ca2+-ATPase is an essential ion pump involved in calcium homeostasis.
Purpose of the Study:
- To investigate the impact of Ca2+-ATPase on the shape fluctuations of giant vesicles.
- To quantify the changes in membrane bending modulus induced by the protein.
- To measure the active forces generated by Ca2+-ATPase upon activation.
Main Methods:
- Utilized the micropipette aspiration technique to manipulate and measure vesicle properties.
- Experimentally determined the bending modulus of giant vesicles with and without Ca2+-ATPase.
- Quantified active force dipoles associated with protein-induced membrane fluctuations.
Main Results:
- Observed a substantial renormalization of the bending modulus in the presence of Ca2+-ATPase.
- Provided the first quantitative measurement of the active force dipole generated by activated Ca2+-ATPase.
- Demonstrated that adenosine 5'-triphosphate (ATP) activation amplifies vesicle fluctuations.
Conclusions:
- Ca2+-ATPase significantly influences the mechanical properties and dynamics of giant vesicle membranes.
- The study provides new insights into protein-mediated membrane remodeling and active force generation.
- Findings contribute to understanding the biophysical mechanisms underlying membrane protein function.