Lipoproteins containing apolipoprotein A-IV: composition and relation to cholesterol esterification.
In order to investigate the relationship of lipid and apolipoprotein composition to cholesterol esterification in lipoproteins containing apolipoprotein (apo) A-IV, apo A-containing lipoprotein particles were isolated from fresh human plasma using a system of sequential immunoaffinity chromatography. Plasma was first depleted of apo B- and apo E-containing lipoproteins. Four major subpopulations of apo A-containing lipoprotein particles were separated: Lp A-I, Lp A-I: A-II, Lp A-IV and Lp A-I: A-IV: A-II. Lp A-IV and Lp A-I: A-IV: A-II contained less total lipid, less cholesterol and more triacylglycerol than Lp A-I and Lp A-I: A-II. Lp A-IV and Lp A-I: A-IV: A-II contained more sphingomyelin and less phosphatidylcholine than Lp A-I and Lp A-I: A-II and were richer in (16:0 + 18:0) saturated fatty acids. Among these isolated lipoprotein particles, Lp A-IV contained the highest lecithin: cholesterol acyltransferase (LCAT) activity per micrograms of protein. Cholesterol esterification rates were 2.6 +/- 0.5, 5.3 +/- 0.4 and 0.8 +/- 0.2 mumol of cholesterol per hour per mg of lipoproteins for Lp A-IV, Lp A-I and Lp A-I: A-II, respectively. The apolipoprotein and lipid composition and LCAT activity of Lp A-IV suggest that this lipoprotein may be a source of cholesterol esterification in plasma.
Duverger
N
N
Institut Pasteur, INSERM U325, Lille, France.
Ghalim
N
N
Theret
N
N
Fruchart
J C
JC
Castro
G
G
D000328:Adult; D001054:Apolipoproteins A / Q000032:analysis*; D002788:Cholesterol Esters / Q000097:blood / Q000737:chemistry*; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D008297:Male; D010641:Phenotype; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000032:analysis
D001054:Apolipoproteins A; D002788:Cholesterol Esters; D008075:Lipoproteins, HDL; C022205:apolipoprotein A-IV; D007862:Phosphatidylcholine-Sterol O-Acyltransferase