A Synthetic Peptide-Based Assay System for Detecting Binding between CD36 and an Oxidized Low-Density Lipoprotein

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CD36 is an integral membrane protein that mediates the cellular uptake of oxidized low-density lipoprotein (oxLDL) through recognition of the oxidized glycerophospholipids (oxPLs) formed during LDL oxidation. We aimed to devise an assay system to detect binding between CD36 and oxLDL/oxPL without using recombinant proteins. A peptide corresponding to amino-acid residues 149–168 of mouse CD36 with biotin at its N-terminus (named biotin-CD36_149–168) and variants of it were synthesized and immobilized onto streptavidin-coated plates. oxLDL labeled with Alexa-Fluor-488 bound specifically and saturably to immobilized biotin-CD36_149–168, but poorly or not at all to the variants, such as that with a scrambled amino-acid sequence. The binding of fluorescence-labeled oxLDL to biotin-CD36_149–168 was inhibited efficiently by an oxPL species, but not by a nonoxidized glycerophospholipid. This assay system using biotin-CD36_149–168 provides a convenient means not only of characterizing binding profiles between CD36 and oxLDL/oxPL but also of finding competitors for the binding.