Sterol structure determines the separation of phases and the curvature of the liquid-ordered phase in model membranes
- 18 February 2005
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 102 (9), 3272-3277
- https://doi.org/10.1073/pnas.0408215102
Abstract
The existence of lipid rafts in biological membranes in vivo is still debated. In contrast, the formation of domains in model systems has been well documented. In giant unilamellar vesicles (GUVs) prepared from ternary mixtures of dioleoyl-phosphatidylcholine/sphingomyelin/cholesterol, a clear separation of liquid-disordered and sphingomyelin-enriched, liquid-ordered phases could be observed. This phase separation can lead to the fission of the liquid-ordered phase from the vesicle. Here we show that in cholesterol-containing GUVs, the phase separation can involve dynamic redistribution of lipids from one phase into another as a result of a cross-linking perturbation. We found that the molecular structure of a sterol used for the preparation of GUVs determines (i) its ability to induce phase separation and (ii) the curvature (positive or negative) of the formed liquid-ordered phase. As a consequence, the latter can pinch off to the outside or inside of the vesicle. Remarkably, some mixtures of sterols induce liquid-ordered domains exhibiting both positive and negative curvature, which can lead to a new type of budding behavior in GUVs. Our findings could have implications for the role of sterols in various cell-biological processes such as budding of secretory vesicles, endocytosis, or formation of multivesicular bodies.Keywords
This publication has 48 references indexed in Scilit:
- Steroid Structural Requirements for Stabilizing or Disrupting Lipid DomainsBiochemistry, 2003
- Lipid RaftsCell, 2003
- Probing Lipid Mobility of Raft-exhibiting Model Membranes by Fluorescence Correlation SpectroscopyJournal of Biological Chemistry, 2003
- Partitioning of Lipid-Modified Monomeric GFPs into Membrane Microdomains of Live CellsScience, 2002
- Effect of the Structure of Natural Sterols and Sphingolipids on the Formation of Ordered Sphingolipid/Sterol Domains (Rafts)Journal of Biological Chemistry, 2001
- Structure of Detergent-Resistant Membrane Domains: Does Phase Separation Occur in Biological Membranes?Biochemical and Biophysical Research Communications, 1997
- Sorting of GPI-anchored proteins to glycolipid-enriched membrane subdomains during transport to the apical cell surfaceCell, 1992
- Transmembrane movements of lipidsCellular and Molecular Life Sciences, 1990
- Detergent extraction of cholera toxin and gangliosides from cultured cells and isolated membranesBiochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1982
- Phase equilibriums in binary mixtures of phosphatidylcholine and cholesterolBiochemistry, 1981