Two apolipoprotein E mimetic peptides, ApoE(130-149) and ApoE(141-155)2, bind to LRP1

LRP1 is a cell surface receptor responsible for clearing some 30 known ligands. We have previously shown that each of the three complete LDL receptor-homology domains of the LRP1 extracellular domain (sLRPs) binds apoE-enriched beta-VLDL particles. Here we show that two peptides from the N-terminal receptor binding domain of apoE, which are known to elicit a number of different cellular responses, bind to LRP1. Solution binding assays show that the two peptides, apoE(130-149) and apoE(141-155)(2), interact with each of the sLRPs (2, 3, and 4). Each peptide was found to exhibit the same solution binding characteristics as apoE-enriched beta-VLDL particles. Surface plasmon resonance analyses of the sLRP-apoE peptide interaction show that both peptides bind the sLRPs with K-D values in the 100 nM range, a value similar to the effective concentration required for observation of the cellular responses. Consistent with results from mutagenesis studies of binding of apoE to LDLR, apoE(130-149,Arg142Glu) bound with a K-D similar to that of the wild-type sequence, while apoE(130-149,Lys143Glu) showed a 10-fold decrease in K-D. Each of the peptides bound heparin, and heparin competed for sLRP binding.