Isolation and specificity of a Mr 74,000 cholesteryl ester transfer protein from human plasma.

A cholesteryl ester transfer protein was isolated from human plasma whose ligand specificity, molecular weight, and amino acid composition are significantly different from those of proteins previously reported to have this activity. The protein, purified about 100,000-fold from plasma, is rich in hydrophobic amino acids, especially leucine. It has a molecular weight of 74,000 and an isoelectric point of 5.2. The protein's transfer rate for cholesteryl ester between each of the major plasma lipoprotein classes is similar, and rapid compared to the transfer of triacyglycerol, regardless of the overall lipid composition of the donor and acceptor lipoprotein. These data suggest that this protein functions primarily in the transfer of cholesteryl esters between plasma lipoproteins.