Figure 1.
Oil drop model of plasma lipoproteins. Each lipoprotein comprises a neutral lipid core surrounded by a surface monolayer of proteins and phospholipids. LDL: low-density lipoprotein; HDL: high-density lipoprotein; VLDL: very low-density lipoprotein; PL: phospholipid; CE: cholesteryl ester
Figure 2.
Lipid transfer reaction coordinate. (A) A monoacyl lipid resides in the outer phospholipid monolayer of a membrane or lipoprotein. (B) With sufficient free energy, the lipid escapes the membrane but remains noncovalently tethered, thereby reducing its rotational freedom. (C) As it diffuses into the surrounding aqueous phase, the lipid reaches a lower free energy.
Figure 3.
Electron cryomicroscopy reconstruction of reconstituted HDL (rHDL). (A) Isosurface representation of rHDL viewed in an en face orientation. The diameter of the particle is ~360 Å. (B) Isosurface representation of the rHDL particle viewed laterally; the thickness is ~45 Å, the same as that of a single dimyristoylphosphatidylcholine bilayer. (C, D) Isosurface representation of rHDL scaled to diameter = 96 Å, but preserving thickness viewed in en face and lateral orientations assuming the same thickness but different density.