This study addresses the question of whether cholesteryl ester transfer protein and apolipoprotein D are identical. The data presented show that these two proteins do not co-purify during hydrophobic and cationic exchange chromatography and are readily separated by molecular sieve chromatography or electrophoresis. Furthermore, the precipitation of apolipoprotein D by specific antisera did not diminish the transfer activity of lipoprotein-deficient plasma. We conclude that apolipoprotein D and cholesteryl ester transfer protein have significantly different physicochemical properties.
