CONICET | Buscador de Institutos y Recursos Humanos

The cell membrane is composed by lipids, proteins, and carbohydrates. The amphipathic nature of lipid molecules allows them to pack tightly while maintaining a high degree of lateral mobility. In addition, lipids are organized into microdomains (e.g., rafts) that may provide important boundaries that organize integral membrane proteins. Cholesterol is a small lipid molecule that nestles among the hydrophobic tails of the phospholipids in the interior of the membrane. It is know to make the membrane more fluid and at the same time it is indicated as the main constituent of lipid rafts. The decrease in fluidity of the membrane after removing cholesterol from the membranes is normally used as an indication for the involvement of lipid raft in the process under study. In artificial systems depending on composition of the bilayer, the presence of cholesterol may increase or decrease their fluidity (measured as water content). In this report, we show that this observation is also valid in natural membranes. We used Laurdan Generalized Polarization Microscopy to measure water content in the membrane of several cell types before and after removing cholesterol using methyl-â-cyclodextrins and reconstituted HDL particles. Our results indicate that removal of cholesterol from the cellular membrane produce either increase or decrease in fluidity depending on the membrane composition. HDL particles. Our results indicate that removal of cholesterol from the cellular membrane produce either increase or decrease in fluidity depending on the membrane composition. â-cyclodextrins and reconstituted HDL particles. Our results indicate that removal of cholesterol from the cellular membrane produce either increase or decrease in fluidity depending on the membrane composition.