Purification and characterization of low density lipoprotein containing apolipoprotein B-48 from the plasma of an apoE-deficient patient

Abstract

The plasma low density lipoprotein (LDL) of an apolipoprotein (apo) E-deficient patient was reported to contain apoB-48 (D. Kurosaka et al., Atherosclerosis 1988;88:15), which is a structural protein of chylomicrons and is not present in the fasting plasma LDL of normal subjects. We separated the LDLs containing apoB-48 (apoB-48 LDL) and apoB-100 (apoB-100 LDL) from the plasma of this patient using heparin-sepharose column chromatography. The apoB-48 LDL contained apoA-I, apoA-IV, and apoCs besides apoB-48. There were no differences in size and lipid composition of the apoB-48 and the apoB-100 LDLs, both of which contained more triglyceride than LDL from normal subjects. After incubation with apoE, the apoB-48 LDL contained twice the amount of apoE than the apoB-100 LDL and showed a marked decrease in apoA-I and apoA-IV content. These results suggest that lipoproteins containing apoB-48 in normal subjects can be quickly taken up through an apoE-mediated receptor mechanism after receiving apoE in exchange for apoA-I and A-IV.