Cholesterol domains in biological membranes

Membrane cholesterol is distributed asymmetrically both within the cell or within cellular membranes. Elaboration of intracellular cholesterol trafficking, targeting and intramembrane distribution has been spurred by both molecular and structural approaches. The expression of recombinant sterol carrier proteins in L-cell fibroblasts has been especially useful in demonstrating for the first time that such proteins actually elicit intracellular and intra-plasma membrane redistribution of sterol. Additional advances in the use of native fluorescent sterols allowed resolution of transbilayer and lateral cholesterol domains in plasma membranes from cultured fibroblasts, brain synaptosomes and erythrocytes. In all three cell surface membranes, cholesterol is enriched in the inner, cytofacial leaflet. Up to three different cholesterol domains have been identified in the lateral plane of the plasma membrane: a fast exchanging domain comprising less than 10% of cholesterol, a slowly exchanging domain comprising ab...