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Biochemistry. 2006 Jan 17;45(2):381-90.

Self-assembly of HEK cell-secreted ApoE particles resembles ApoE enrichment of lipoproteins as a ligand for the LDL receptor-related protein.

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  • 1Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612, USA.

Abstract

Recent studies have shown that the lipidation and assembly state of apolipoprotein E (apoE) determine receptor recognition and amyloid-beta peptide (Abeta) binding. We previously demonstrated that apoE secreted by HEK cells stably expressing apoE3 or apoE4 (HEK-apoE) binds Abeta and inhibits Abeta-induced neurotoxicity by an isoform-specific process that requires apoE receptors. Here we characterized the structure of HEK-apoE assemblies and determined their receptor binding specificity. By chromatography, HEK-apoE elutes in high molecular mass fractions and is the size of plasma HDL, consistent with a multiprotein assembly. No lipid was associated with these apoE assemblies. Several methods for analyzing receptor binding indicate that HEK-apoE is a ligand for low-density lipoprotein (LDL) receptor-related protein (LRP) but not the LDL receptor. This suggests that self-assembly of apoE may induce a functional conformation necessary for binding to LRP. Our results indicate that, in addition to lipid content, the assembly state of apoE influences Abeta binding and receptor recognition.

PMID:
16401069
[PubMed - indexed for MEDLINE]
PMCID:
PMC2564845
Free PMC Article
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