Preferential redistribution of lipoprotein-unassociated apoA-IV to an HDL subpopulation with a high degree of LCAT modification.
The relationship between LCAT mediated HDL modification and the redistribution of lipoprotein-unassociated apoA-IV to HDL was investigated in vitro. Immunoaffinity-isolated rat lipoprotein-unassociated apoA-IV was added to apoB-, apoE-, apoA-IV depleted, [3H]cholesterol labelled rat plasma and incubated at 37 degrees C. The addition of lipoprotein-unassociated apoA-IV resulted in a modest (10%) but significant reduction in the rate of cholesterol esterification. Incubations conducted in the presence of active LCAT led to a time-dependent increase in the amount of the 3H label retained by an anti-apoA-IV immunoaffinity column. Lipoproteins retained by the anti-apoA-IV immunoaffinity column had experienced a greater conversion of [3H]cholesterol to [3H]cholesteryl esters (48% esterification at 30 min) than the unretained lipoproteins (19% esterification at 30 min). These data suggest that during the course of LCAT-induced cholesterol esterification, lipoprotein-unassociated apoA-IV transfers to a subpopulation of HDL which has been modified by LCAT to a greater extent than the remaining HDL. Further analysis of the data demonstrates that 48% cholesterol esterification is sufficient to allow apoA-IV to be accommodated on the surface of an HDL particle.
Lefevre
M
M
Department of Physiology, Louisiana State University Medical Center, New Orleans 70112-2822.
Goudey-Lefevre
J C
JC
Roheim
P S
PS
D000818:Animals; D001053:Apolipoproteins / Q000097:blood; D001054:Apolipoproteins A / Q000097:blood* / Q000302:isolation & purification; D001055:Apolipoproteins B / Q000097:blood; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D002846:Chromatography, Affinity; D004951:Esterification; D066298:In Vitro Techniques; D008075:Lipoproteins, HDL / Q000097:blood*; D008297:Male; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000097:blood*; D051381:Rats
D001053:Apolipoproteins; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D008075:Lipoproteins, HDL; C022205:apolipoprotein A-IV; D002784:Cholesterol; D007862:Phosphatidylcholine-Sterol O-Acyltransferase