Human low density lipoprotein: the mystery of core lipid packing

LDL particles are very fascinating macromolecular assemblies of apolipoprotein B-100 and lipids and their structural features have attracted the attention of scientists for decades. There is a general consensus in the literature that LDL particles are organized into two major compartments, namely an apolar lipid core, comprised primarily of cholesteryl esters, triglycerides, and some free unesterified cholesterol and an outer amphipathic shell that surrounds the apolar core. This outer shell is composed of a phospholipid monolayer containing most of the free unesterified cholesterol and one single copy of apolipoprotein B-100 [for review, see Ref. (1)]. LDLs are highly heterogeneous in nature, varying in buoyant density, size, surface charge, and chemical composition (2). These intrinsic properties are intimately related to intravascular metabolism of LDL (3), atherogenicity (4), and the fate of the particle in the subendothelial space (5).