Apolipoprotein E (apoE) mediates the efficient catabolism of the chylomicron remnants very low-density lipoprotein and low-density lipo-protein from the circulation, and thede novo biogenesis of high-density lipoprotein. Lipid-bound apoE is the natural ligand for the low-density lipoprotein receptor (LDLr), LDLr-related protein 1 and other scavenger receptors.