Defective hepatic lipoprotein receptor binding of beta-very low density lipoproteins from type III hyperlipoproteinemic patients. Importance of apolipoprotein E

J Biol Chem. 1984 Jan 25;259(2):860-9.


Apolipoprotein (apo-) E2 and beta-migrating very low density lipoproteins (beta-VLDL) (which were isolated from type III hyperlipoproteinemic subjects) both demonstrated defective binding to apo-E and apo-B,E receptors on dog liver membranes and to apo-B,E low density lipoproteins (LDL) receptors on fibroblasts. The defective binding activity of the apo-E2 and beta-VLDL varied from very poor to nearly normal. The ability of the beta-VLDL to interact with hepatic apo-E receptors was enhanced by the addition of normal apo-E3 to the beta-VLDL. Furthermore, cysteamine treatment of the apo-E2 in beta-VLDL enhanced binding of the beta-VLDL to both apo-E and apo-B,E receptors. The importance of apo-E in mediating the receptor binding of beta-VLDL to these receptors was confirmed by using monoclonal antibodies. The residual binding activity of beta-VLDL to apo-E and apo-B,E receptors was inhibited by greater than 90% with anti-apo-E, while the addition of anti-apo-B had little effect. The apo-B in the beta-VLDL was capable of binding to apo-B,E receptors after the hydrolysis of the beta-VLDL triglycerides with milk lipoprotein lipase. Lipase treatment yielded, two subfractions of beta-VLDL. One fraction (d = 1.02 to 1.03 g/ml) was enriched with apo-B100; the other fraction (d less than 1.006 g/ml) was enriched with apo-B48 and apo-E2. Significantly increased amounts of the apo-B100-enriched fraction bound to apo-B,E receptors. Inhibition of this binding caused by the addition of anti-apo-B indicated that the binding activity of this subfraction was mediated by apo-B100. The apo-B48-enriched fraction did not show a significant increase in receptor binding, suggesting that apo-B48 does not bind to these receptors. In a control experiment, it was shown that triglyceride-rich VLDL, which contain normal apo-E3 and apo-B100, bind significantly to both liver apo-E receptors and fibroblast apo-B,E receptors. This binding activity was inhibited by greater than 90% with anti-apo-E. Lipase hydrolysis of the VLDL did not further enhance their receptor-binding activity. These results demonstrate that apo-E, and not apo-B, is the major determinant mediating the receptor-binding activity of cholesterol-rich beta-VLDL and triglyceride-rich VLDL.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apolipoprotein E2
  • Apolipoprotein E3
  • Apolipoproteins / analysis
  • Apolipoproteins / metabolism*
  • Apolipoproteins B
  • Apolipoproteins E
  • Calcium / metabolism
  • Cholestyramine Resin / pharmacology
  • Dogs
  • Humans
  • Hyperlipoproteinemia Type III / metabolism*
  • Lipoproteins, VLDL / analysis
  • Lipoproteins, VLDL / metabolism*
  • Liver / metabolism*
  • Low Density Lipoprotein Receptor-Related Protein-1
  • Receptors, Cell Surface / metabolism*
  • Receptors, Lipoprotein*


  • Apolipoprotein E2
  • Apolipoprotein E3
  • Apolipoproteins
  • Apolipoproteins B
  • Apolipoproteins E
  • Lipoproteins, VLDL
  • Low Density Lipoprotein Receptor-Related Protein-1
  • Receptors, Cell Surface
  • Receptors, Lipoprotein
  • apolipoprotein B,E receptor
  • Cholestyramine Resin
  • Calcium