HDL biology
A review names CETP among three plasma factors that release lipid-poor apoA-I from HDL during remodeling, the key acceptor for ABCA1-mediated cholesterol efflux (Arterioscler Thromb Vasc Biol 2004)
Original title: Formation and metabolism of prebeta-migrating, lipid-poor apolipoprotein A-I
The preferred extracellular acceptor of cell phospholipid and unesterified cholesterol in ABCA1-transporter-mediated efflux is a monomolecular, prebeta-migrating, lipid-poor or lipid-free form of apolipoprotein A-I (apoA-I), distinct from the prebeta-migrating discoidal HDL containing two or three apoA-I molecules that forms a minor HDL component in human plasma. While ABCA1-mediated cellular efflux has been studied extensively, less attention has been paid to the origin and metabolism of this lipid-free/lipid-poor apoA-I acceptor. In vitro evidence indicates that this monomolecular apoA-I dissociates from HDL during remodeling by plasma factors including cholesteryl ester transfer protein (CETP), hepatic lipase, and phospholipid transfer protein, with the dissociation rate influenced by particle phospholipid composition and apoA-II presence.
Original abstract
The preferred extracellular acceptor of cell phospholipids and unesterified cholesterol in the process mediated by the ATP-binding cassette A1 (ABCA1) transporter is a monomolecular, prebeta-migrating, lipid-poor or lipid-free form of apolipoprotein (apo) A-I. This monomolecular form of apoA-I is quite distinct from the prebeta-migrating, discoidal high-density lipoprotein (HDL) that contains two or three molecules of apoA-I per particle and which are present as minor components of the HDL fraction in human plasma. The mechanism of the ABCA1-mediated efflux of phospholipid and cholesterol from cells has been studied extensively. In contrast, much less attention has been given to the origin and subsequent metabolism of the acceptor lipid-free/lipid-poor apoA-I. There is a substantial body of evidence from studies conducted in vitro that a monomolecular, lipid-free/lipid-poor form of apoA-I dissociates from HDL during the remodeling of HDLs by plasma factors such as cholesteryl ester transfer protein, hepatic lipase, and phospholipid transfer protein. The rate at which apoA-I dissociates from HDL is influenced by the phospholipid composition of the particles and by the presence of apoA-II. This review describes current knowledge regarding the formation, metabolism, and regulation of monomolecular, lipid-free/lipid-poor apoA-I in plasma.
Summary written by cetpinhibition.org from the published abstract; figures as published. Page updated 19 August 2026. Methods.