Cholesteryl ester and apolipoprotein E transfer between human high density lipoproteins and chylomicrons.
The transfer of cholesteryl esters and apolipoprotein E has been studied between plasma HDL and chylomicrons isolated either from ascitic fluid or from the plasma of a patient with type V hyperlipoproteinemia. Whereas apolipoprotein E transfer was rapid and occurred at low temperature, cholesteryl ester transfer was suppressed at 4 degrees C. Apolipoprotein E transfer did not depend upon the presence of cholesteryl ester transfer protein and was in fact inhibited by the partially purified preparation of this protein. Apolipoprotein E transfer was not increased by reduction with dithiothreitol. The transfer of cholesteryl esters increased sharply at a chylomicron to HDL ratio of cholesteryl ester above 1/10, a value which may be of physiological significance at the peak of postprandial lipemia. At this ratio, the transfer of apolipoprotein E was minimal and increased only at ratios above 2/1. From these results, it is concluded that there is no connection between apolipoprotein E and cholesteryl ester transfer from HDL to chylomicrons. It is, therefore, proposed that whereas chylomicron apolipoprotein E is acquired rapidly and mostly in the lymphatic system, the concentration of chylomicron cholesteryl esters increases significantly and independently in the circulation.
D001053:Apolipoproteins / Q000097:blood*; D001057:Apolipoproteins E; D002250:Carbon Radioisotopes; D002788:Cholesterol Esters / Q000097:blood*; D002914:Chylomicrons / Q000097:blood*; D003080:Cold Temperature; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood*
D001053:Apolipoproteins; D001057:Apolipoproteins E; D002250:Carbon Radioisotopes; D002788:Cholesterol Esters; D002914:Chylomicrons; D007457:Iodine Radioisotopes; D008075:Lipoproteins, HDL