Apolipoprotein Specificity for Lipid Efflux by the Human ABCAI Transporter

• Published in: Biochemical and biophysical research communications 2001-01, Vol.280 (3), p.818-823
• Main Authors: Remaley, Alan T., Stonik, John A., Demosky, Steven J., Neufeld, Edward B., Bocharov, Alexander V., Vishnyakova, Tatyana G., Eggerman, Thomas L., Patterson, Amy P., Duverger, Nicholas J., Santamarina-Fojo, Silvia, Brewer, H.Bryan
• Format: Article
• Language: English
• Subjects: ABC transporters; ABCAI; Apolipoprotein A-I - metabolism; Apolipoprotein A-II - metabolism; Apolipoproteins - metabolism; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Biological Transport, Active; Gene Expression; Green Fluorescent Proteins; HDL; HeLa Cells; Humans; Kinetics; Lipid Metabolism; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Tangier disease; Transfection
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.2000.4219

ABCAI, a member of the ATP binding cassette family, mediates the efflux of excess cellular lipid to HDL and is defective in Tangier disease. The apolipoprotein acceptor specificity for lipid efflux by ABCAI was examined in stably transfected Hela cells, expressing a human ABCAI–GFP fusion protein. ApoA-I and all of the other exchangeable apolipoproteins tested (apoA-II, apoA-IV, apoC-I, apoC-II, apoC-III, apoE) showed greater than a threefold increase in cholesterol and phospholipid efflux from ABCAI–GFP transfected cells compared to control cells. Expression of ABCAI in Hela cells also resulted in a marked increase in specific binding of both apoA-I (Kd = 0.60 μg/mL) and apoA-II (Kd = 0.58 μg/mL) to a common binding site. In summary, ABCAI-mediated cellular binding of apolipoproteins and lipid efflux is not specific for only apoA-I but can also occur with other apolipoproteins that contain multiple amphipathic helical domains.