Intracellular sterol binding proteins: Cholesterol transport and membrane domains

Regulation intracellular cholesterol transport is not well understood. Part of the difficulty is that not only is the intracellular distribution of cholesterol not uniform, but even within membranes cholesterol has an asymmetric transbilayer and lateral distribution. Although both vesicular and protein mediated pathways for cholesterol movement are recognized, the role of intracellular cholesterol binding proteins in cytosolic cholesterol trafficking remains largely unresolved. Recent work from this and other laboratories demonstrates that these cholesterol binding proteins are involved in cholesterol uptake and intracellular trafficking. Immunocytochemical evidence supports the presence of significant amounts of proteins such as the sterol carrier protein-2 outside of peroxisomes.