title: Apolipoprotein E isoform-specific binding to the low-density lipoprotein receptor.
abstract: 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.
authors.affiliation: Center for Prevention of Obesity, Diabetes, and Cardiovascular Disease, Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.
authors.forename: Taichi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Hyung Won
authors.initials: HW
authors.lastname: Choi
authors.forename: Robert O
authors.initials: RO
authors.lastname: Ryan
mesh_terms: D016632:Apolipoprotein A-I / Q000378:metabolism; D053318:Apolipoprotein E3 / Q000378:metabolism; D001057:Apolipoproteins E / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D004134:Dimyristoylphosphatidylcholine / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D016632:Apolipoprotein A-I; D053318:Apolipoprotein E3; D001057:Apolipoproteins E; D010743:Phospholipids; D020033:Protein Isoforms; D011973:Receptors, LDL; D011994:Recombinant Proteins; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine