Fig. 5.

Schematic drawing of HDL formation by ABCA1. ABCA1 monomer diffuses freely and translocates lipids on the PM in an ATPase-dependent manner (1). ABCA1, which reserves lipids within or nearby, is immobilized as a dimer by being tethered to actin cytoskeletons (2). Lipid-free apoA-I binds to the ABCA1 dimer (3). Lipids are loaded onto apoA-I, and the ABCA1 dimer dissociates into monomers (4). Lipidated apoA-I spontaneously binds to the PM and is in equilibrium between the PM and the media (5).