Apolipoprotein E is the major physiological activator of lecithin-cholesterol acyltransferase (LCAT) on apolipoprotein B lipoproteins
Zhao, Y.; Thorngate, F.E.; Weisgraber, K.H.; Williams, D.L.; Parks, J.S.
Biochemistry 44(3): 1013-1025
ISSN/ISBN: 0006-2960 PMID: 15654758 DOI: 10.1021/bi0481489
Our previous studies have indicated that lecithin-cholesterol acyltransferase (LCAT) contributes significantly to the apoB lipoprotein cholesteryl ester (CE) pool. Cholesterol esterification rate (CER) in apoA-I-/- apoE-/- mouse plasma was <7% that of C57B1/6 (B6) mouse plasma, even though apoA-I-/-apoE-/- plasma retained1 /3 the amount of B6 LCAT activity. This suggested that lack of LCAT enzyme did not explain the low CER in apoA-I-/- apoE-/- mice and indicated that apoE and apoA-I are the only major activators of LCAT in mouse plasma. Deleting apoE on low-density lipoprotein (LDL) reduced CER (1% free cholesterol (FC) esterified/h) compared to B6 (6% FC esterified/h) and apoA-I-/- (11% FC esterified/h) LDL.