Formation and metabolism of prebeta-migrating, lipid-poor apolipoprotein A-I.
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.
Heart Research Institute, Camperdown, Sydney, NSW, Australia.
Kerry-Anne
KA
Rye
Philip J
PJ
Barter
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D016632:Apolipoprotein A-I / Q000097:blood* / Q000737:chemistry; D016633:Apolipoprotein A-II / Q000097:blood; D001646:Bile / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008049:Lipase / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000097:blood / Q000737:chemistry; D008079:Lipoproteins, VLDL / Q000097:blood* / Q000737:chemistry; D008099:Liver / Q000201:enzymology; D008565:Membrane Proteins / Q000378:metabolism; D049294:Phospholipid Transfer Proteins / Q000378:metabolism; D010743:Phospholipids / Q000097:blood; D011971:Receptors, Immunologic / Q000378:metabolism; D051116:Receptors, Scavenger; D014280:Triglycerides / Q000097:blood
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; D008075:Lipoproteins, HDL; D008079:Lipoproteins, VLDL; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D011971:Receptors, Immunologic; D051116:Receptors, Scavenger; D014280:Triglycerides; D002784:Cholesterol; D008049:Lipase