Secretion of cholesteryl ester transfer protein-lipoprotein complexes by human HepG2 hepatocytes.
We have employed immunoaffinity chromatography to characterize the distribution of cholesteryl ester transfer activity in particles secreted by HepG2 hepatocytes. HepG2-secreted cholesteryl ester transfer activity is associated with apoprotein (apo) A-I (58%) as well as apo A-II (55%), and is not associated with apo B or E. In contrast, our previous studies have shown that most (88%) cholesteryl ester transfer activity in human plasma is associated with apo A-I whereas very little (7%) is associated with apo A-II. Thus, the distribution of cholesteryl ester transfer activity in plasma particles likely reflects active remodeling of nascent particles in the plasma compartment. Further data suggested that HepG2 cells secrete a lipid transfer inhibitor activity which is associated with apo E-containing lipoprotein particles. This inhibitory activity is heat labile.
Faust
R A
RA
Department of Pathology, University of Washington School of Medicine, Seattle 98104-2499.
Cheung
M C
MC
Albers
J J
JJ
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D001053:Apolipoproteins / Q000378:metabolism*; D001054:Apolipoproteins A / Q000378:metabolism; D001055:Apolipoproteins B / Q000378:metabolism; D001057:Apolipoproteins E / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D053480:Cholesterol Ester Transfer Proteins; D002846:Chromatography, Affinity; D006023:Glycoproteins; D006801:Humans; D011863:Radioimmunoassay
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D001053:Apolipoproteins; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D001057:Apolipoproteins E; C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; C030363:lipid transfer protein