The SCARB family of scavenger receptors (CD36, SR-B1 and LIMP II) are broadly expressed proteins that serve as receptors for a number of ligands including the lipoproteins HDL and LDL. These lipoproteins control the homeostatic balance of cholesterol levels in the body and their proper function is important for protection against atherosclerosis. By determining the crystal structure of the SCARB receptors we and our collaborators showed that they contain a hydrophobic tunnel through which cholesterol can directly transit from the lipoprotein to the plasma membrane. Future studies will involve further characterization of this novel mode of lipid transport, and determination of the relative contributions of endocytosis and direct transport in cholesterol homeostasis.
