Cd36, a class B scavenger receptor, functions as a monomer to bind acetylated and oxidized low-density lipoproteins

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Cd36 (collaboration of differentiation 36) is an integral membrane protein involved in various physiological functions.
• Dysregulation of Cd36 is implicated in diseases like insulin resistance, diabetes, and atherosclerosis.
• Cd36's function may depend on its interactions within detergent-resistant membrane microdomains.

Purpose of the Study:

• To investigate the biophysical properties and ligand-binding capabilities of purified Cd36.
• To determine if Cd36 requires accessory proteins for ligand interaction.
• To assess the suitability of purified Cd36 for structural studies and drug screening.

Main Methods:

• Overexpression of Cd36 in insect cells.
• Purification of recombinant Cd36 to homogeneity.
• Analysis of protein stability and solubility using various detergents (e.g., octylglucoside).
• Analytical ultracentrifugation to determine protein quaternary structure.
• Solid-phase ligand-binding assay using acetylated and oxidized low-density lipoproteins.

Main Results:

• Octylglucoside provided optimal stability for Cd36.
• Analytical ultracentrifugation confirmed Cd36 exists as a monomer.
• Purified monomeric Cd36 demonstrated high-affinity binding to acetylated and oxidized LDL.
• Ligand binding is an intrinsic property of the monomeric Cd36 fold, not requiring accessory proteins.

Conclusions:

• Cd36 functions as a monomer in binding ligands like modified LDL.
• The purified, functional Cd36 is amenable to crystallization for structural determination.
• The in vitro ligand-binding assay is a valuable tool for identifying molecules targeting Cd36 in atherogenesis.