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Lipid-bilayer membranes are formed by self-assembly processes. The molecular interactions within the bilayer and with the environment impart a unique trans-bilayer lateral pressure profile and provide a set of physical mechanisms for formation of lipid domains and laterally differentiated regions in the plane of the membrane. Results from a number of(More)
Very low density lipoprotein receptor (VLDL-R) was found to be expressed in bovine mammary gland and the human breast carcinoma cell line MCF-7 as an M(r) 105,000 variant, and in Chinese hamster ovary (CHO) cells transfected with human VLDL-R cDNA as an M(r) 130,000 variant. The receptor was purified by ligand affinity chromatography with immobilized M(r)(More)
We have reconstituted functional Na(+)/K(+)-ATPase (NKA) into giant unilamellar vesicles (GUVs) of well-defined binary and ternary lipid composition including cholesterol. The activity of the membrane system can be turned on and off by ATP. The hydrolytic activity of NKA is found to depend on membrane phase, and the water relaxation in the membrane on the(More)
The effect of temperature on the lateral structure of lipid bilayers composed of porcine brain ceramide and 1-palmitoyl 2-oleoyl-phosphatidylcholine (POPC), with and without addition of cholesterol, were studied using differential scanning calorimetry, Fourier transformed infrared spectroscopy, atomic force microscopy, and confocal/two-photon excitation(More)
An atomic force and fluorescence microscopy investigation of the structure of spin-coated lipid films is presented. In the surface of the dry film, lipids are found to orient in a conformation where acyl chains are pointing outward while laterally the individual layers of the multilamellar film exhibit a dewetting pattern similar to what is found in polymer(More)
Pulmonary surfactant, the lipid-protein material that stabilizes the respiratory surface of the lungs, contains approximately equimolar amounts of saturated and unsaturated phospholipid species and significant proportions of cholesterol. Such lipid composition suggests that the membranes taking part in the surfactant structures could be organized(More)
A number of morphological and statistical aspects of domain formation in singly and doubly supported ternary membranes have been investigated. Such ternary membranes produce macroscopic phase separation in two fluid phases and are widely used as raft models. We find that membrane interactions with the support surface can have a critical influence on the(More)
The fluorescent sterol dehydroergosterol (DHE) is often used as a marker for cholesterol in cellular studies. We show by vesicle fluctuation analysis that DHE has a lower ability than cholesterol to stiffen lipid bilayers suggesting less efficient packing with phospholipid acyl chains. Despite this difference, we found by fluorescence and atomic force(More)
The behavior of a fluid supported membrane during hydrolysis by phospholipase A(2) is for the first time visualized by time-resolved fluorescence imaging. After a lag phase, hydrolysis proceeds from the boundary of existing holes and via nucleation of new holes. During subsequent hydrolysis, the shape of the membrane boundary is determined both by(More)
Dynamic force spectroscopy makes it possible to measure the breaking of single molecular bonds or the unfolding of single proteins subjected to a time-dependent pulling force. The force needed to break a single bond or to unfold a domain in a protein depends critically on the time dependence of the applied force. In this way the elastic response couples to(More)