Identification of the low density lipoprotein receptor-binding site in apolipoprotein B100 and the modulation of its binding activity by the carboxyl terminus in familial defective apo-B100

J Clin Invest. 1998 Mar 1;101(5):1084-93. doi: 10.1172/JCI1847.


Familial defective apolipoprotein B100 (FDB) is caused by a mutation of apo-B100 (R3500Q) that disrupts the receptor binding of low density lipoproteins (LDL), which leads to hypercholesterolemia and premature atherosclerosis. In this study, mutant forms of human apo-B were expressed in transgenic mice, and the resulting human recombinant LDL were purified and tested for their receptor-binding activity. Site-directed mutagenesis and other evidence indicated that Site B (amino acids 3,359-3,369) binds to the LDL receptor and that arginine-3,500 is not directly involved in receptor binding. The carboxyl-terminal 20% of apo-B100 is necessary for the R3500Q mutation to disrupt receptor binding, since removal of the carboxyl terminus in FDB LDL results in normal receptor-binding activity. Similarly, removal of the carboxyl terminus of apo-B100 on receptor-inactive VLDL dramatically increases apo-B-mediated receptor-binding activity. We propose that the carboxyl terminus normally functions to inhibit the interaction of apo-B100 VLDL with the LDL receptor, but after the conversion of triglyceride-rich VLDL to smaller cholesterol-rich LDL, arginine-3,500 interacts with the carboxyl terminus, permitting normal interaction between LDL and its receptor. Moreover, the loss of arginine at this site destabilizes this interaction, resulting in receptor-binding defective LDL.

Publication types

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

MeSH terms

  • Animals
  • Anura
  • Apolipoproteins B / genetics*
  • Apolipoproteins B / immunology
  • Apolipoproteins B / metabolism*
  • Arginine / metabolism
  • Base Sequence
  • Cells, Cultured
  • Chickens
  • Cloning, Molecular
  • DNA Primers / genetics
  • Gene Expression
  • Humans
  • Hyperlipoproteinemia Type II / genetics*
  • Hyperlipoproteinemia Type II / metabolism*
  • Immunoassay
  • Lipoproteins, LDL / blood
  • Lipoproteins, LDL / isolation & purification
  • Lipoproteins, LDL / metabolism*
  • Lipoproteins, VLDL / metabolism
  • Mice
  • Mice, Transgenic
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plasmids
  • Rabbits
  • Receptors, LDL / metabolism
  • Recombinant Proteins / immunology
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Recombination, Genetic
  • Sequence Alignment
  • Sequence Analysis


  • Apolipoproteins B
  • DNA Primers
  • Lipoproteins, LDL
  • Lipoproteins, VLDL
  • Receptors, LDL
  • Recombinant Proteins
  • Arginine