Egg-sphingomyelin and cholesterol form a stoichiometric molecular complex in bilayers of egg-phosphatidylcholine.

The role of sphingomyelin in regulating phase coexistence in complex lipid model membranes: competition between ceramide and cholesterol.

The structure, thermotropic phase behavior, dynamic motion and order parameters of bilayer dispersions of egg phosphatidylcholine, egg sphingomyelin, egg ceramide and cholesterol have been determined. The coexistence of gel, liquid-ordered and liquid-disordered structure has been determined by peak fitting analysis of synchrotron X-ray powder patterns. Order parameters and extent of distributio...

Release of the glycosylphosphatidylinositol-anchored enzyme ecto-5'-nucleotidase by phospholipase C: catalytic activation and modulation by the lipid bilayer.

Many hydrolytic enzymes are attached to the extracellular face of the plasma membrane of eukaryotic cells by a glycosylphosphatidylinositol (GPI) anchor. Little is currently known about the consequences for enzyme function of anchor cleavage by phosphatidylinositol-specific phospholipase C. We have examined this question for the GPI-anchored protein 5'-nucleotidase (5'-ribonucleotide phosphohyd...

Relationships between membrane lipid composition and biological properties of rat myocytes. Effects of aging and manipulation of lipid composition.

Cultures of newborn rat heart myocytes undergo major age-related alterations as demonstrated by comparing 5-6-day-old cells ("young cells") and 14-15-day-old cells ("old cells"). This includes: changes from spherical to elongated shape; sphingomyelin and cholesterol level/cell increase by 100% and 50%, respectively, while the phosphatidylcholine is reduced by 15-20% with almost no change in con...

The role of sterol rings and side chain on the structure and phase behaviour of sphingomyelin bilayers.

The role of the side chain of sterols and the sterol ring structure on the formation of ordered phases of the type observed in membrane rafts has been examined in aqueous dispersions of binary mixtures of sphingomyelin and androsterol. Comparisons have been made with binary systems of cholesterol, stigmasterol, beta-sitosterol, and ergosterol with either sphingomyelin or dipalmitoylphosphatidyl...

Incorporation of Cholesterol in Sphingomyelin- Egg Yolk Phosphatidylcholine Vesicles Has Profound Effects on Detergent-induced Phase Transitions: a Time-course Study by Cryo-transmission Electron Microscopy