title: Phosphatidylcholine transfer protein promotes apolipoprotein A-I-mediated lipid efflux in Chinese hamster ovary cells.
abstract: Phosphatidylcholine transfer protein (PC-TP) is a cytosolic protein of unknown function that catalyzes intermembrane transfer of phosphatidylcholines in vitro. Using stably transfected CHO cells, we explored the influence of PC-TP on apolipoprotein A-I- and high density lipoprotein 3 (HDL(3))-mediated lipid efflux. In proportion to its cellular level of expression, PC-TP accelerated apolipoprotein A-I-mediated phospholipid and cholesterol efflux as pre-beta-HDL particles. PC-TP increased rates of efflux of both lipids by >2-fold but did not affect mRNA levels or the activity of ATP-binding cassette A1, a plasma membrane protein that regulates apolipoprotein A-I-mediated lipid efflux. Overexpression of PC-TP was associated with only slight increases in HDL(3)-mediated phospholipid efflux and no changes in cholesterol efflux. In scavenger receptor BI-overexpressing cells, PC-TP expression minimally influenced apolipoprotein A-I- or HDL(3)-mediated lipid efflux. PC-TP did not affect cellular phospholipid compositions, phosphatidylcholine contents, or phosphatidylcholine synthetic rates. These findings suggest that a physiological function of PC-TP is to replenish the plasma membrane with phosphatidylcholines that are removed during pre-beta-HDL particle formation due to the activity of ATP-binding cassette A1.
authors.affiliation: Department of Biochemistry, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Baez
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Barbour
authors.forename: David E
authors.initials: DE
authors.lastname: Cohen
mesh_terms: D000727:Androgen-Binding Protein; D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism*; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism*; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010713:Phosphatidylcholines / Q000378:metabolism; D049488:Phosphatidylethanolamine Binding Protein; D049294:Phospholipid Transfer Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D000727:Androgen-Binding Protein; D016632:Apolipoprotein A-I; D002352:Carrier Proteins; C511482:PEBP1 protein, human; D010713:Phosphatidylcholines; D049488:Phosphatidylethanolamine Binding Protein; D049294:Phospholipid Transfer Proteins; D011994:Recombinant Proteins