Apolipoprotein E isoform-specific binding to the low-density lipoprotein receptor

• Published in: Analytical biochemistry Vol. 372; no. 2; pp. 222 - 226
• Main Authors: Yamamoto, Taichi, Choi, Hyung Won, Ryan, Robert O.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.01.2008
• Subjects: Apolipoprotein; Apolipoprotein A-I - metabolism; Apolipoprotein E3 - metabolism; Apolipoproteins E - metabolism; Cholesterol - metabolism; Dimyristoylphosphatidylcholine - metabolism; Energy transfer; Fluorescence; Homeostasis; Humans; Isoform; Phospholipids - metabolism; Protein Binding; Protein Isoforms - metabolism; Receptor; Receptors, LDL - metabolism; Recombinant Proteins - metabolism; Substrate Specificity; Fluorescence; Isoform; Apolipoprotein; Receptor; Energy transfer
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/j.ab.2007.09.005

Apolipoprotein E (apoE) is a ligand for members of the low-density lipoprotein receptor (LDLR) family and functions in plasma cholesterol homeostasis. A fluorescence-based assay has been employed in molecular studies of receptor–ligand interactions. Competition experiments revealed isoform-specific differences in binding of lipid-associated apoE N terminal (NT) domain to a recombinant soluble LDLR (sLDLR). In a similar manner, lipid-associated—but not lipid-free—full-length apoE3 showed binding activity to sLDLR. The molecular chaperone, receptor-associated protein, inhibited apoE3–NT–phospholipid complex binding to sLDLR. Kinetic studies of apoE3–NT–phospholipid complex interaction with sLDLR revealed time-dependent effects of apoE–NT isoform binding to sLDLR. The results reveal a discerning method for study of the molecular basis of ligand interactions that likely influence receptor function in maintenance of whole body cholesterol homeostasis.