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Figure 1 Reverse Cholesterol Transport

High-density lipoprotein (HDL) cholesterol promotes and facilitates the process of reverse cholesterol transport (RCT), whereby excess macrophage cholesterol is effluxed to HDL and ultimately returned to the liver for excretion. Efflux to nascent and mature HDL occurs via the transporters ABCA1 and ABCG1, respectively. The HDL cholesterol is returned to the liver via the hepatic receptor SR-BI or by transfer to apolipoprotein (apo) B–containing lipoproteins by the action of cholesteryl ester transfer protein (2). Figure illustrations by Rob Flewell. CETP = cholesterol ester transfer protein; LDL = low-density lipoprotein; LDL-R = low-density lipoprotein receptor; SR-BI = scavenger receptor class B-type I; VLDL = very low-density lipoprotein.