Figure 1.

Schematic diagram of reverse cholesterol transport. Lipid-poor Apolipoprotein (Apo) A1 acquires free cholesterol from peripheral cells via ATP binding cassette transporter (ABC) A1, whereas the ABCG1 and scavenger receptor BI (SR-BI) transporters facilitate cholesterol efflux to high-density lipoprotein (HDL) particles. Free cholesterol is esterified to cholesteryl esters within nascent HDL particles by lecithin-cholesterol acyltransferase (LCAT), thereby generating mature HDL. The liver selectively takes up HDL-associated cholesteryl esters via SR-BI and excretes HDL-derived cholesterol into the bile as free cholesterol or as bile acids after conversion.