The Role of High Density Lipoproteins in Lecithin: Cholesterol Acyltransferase Activity: Perspectives from Tangier Disease

Abstract

Lecithin:cholesterol acyltransferase activity and the lipid composition of VLDL and LDL were examined in five patients homozygous for Tangier disease. The following results were obtained: I. The percentage of cholesterol that was esterified was similar in Tangier and control lipoproteins. II. Linoleic acid was the predominant fatty acid constituent of cholesteryl esters in Tangier plasma. III. Molar cholesterol esterification rates in Tangier plasma were reduced; however, fractional rates of cholesterol esterification were equal to or exceeded those of control plasma. IV. In vitro addition of apoprotein A I and isolated lipoproteins led to a concentration-dependent increase in the intial rates of cholesterol esterification in Tangier plasma. It is concluded that HDI is not an exclusive substrate for the LCAT reaction, and that cholesterol esterification is not impaired in Tangier plasma.

Key Words:

• apolipoproteins
• high density lipoproteins
• lecithin: cholesterol acyltransferase
• Tangier disease