Cd36, a class B scavenger receptor, functions as a monomer to bind acetylated and oxidized low-density lipoproteins.
Cd36 is a small-molecular-weight integral membrane protein expressed in a diverse, but select, range of cell types. It has an equally diverse range of ligands and physiological functions, which has implicated Cd36 in a number of diseases including insulin resistance, diabetes, and, most notably, atherosclerosis. The protein is reported to reside in detergent-resistant microdomains within the plasma membrane and to form homo- and hetero-intermolecular interactions. These data suggest that this class B scavenger receptor may gain functionality for ligand binding, and/or ligand internalization, by formation of protein complexes at the cell surface. Here, we have overexpressed Cd36 in insect cells, purified the recombinant protein to homogeneity, and analyzed its stability and solubility in a variety of nonionic and zwitterionic detergents. Octylglucoside conferred the greatest degree of stability, and by analytical ultracentrifugation we show that the protein is monomeric. A solid-phase ligand-binding assay demonstrated that the purified monomeric protein retains high affinity for acetylated and oxidized low-density lipoproteins. Therefore, no accessory proteins are required for interaction with ligand, and binding is a property of the monomeric fold of the protein. Thus, the highly purified and functional Cd36 should be suitable for crystallization in octylglucoside, and the in vitro ligand-binding assay represents a promising screen for identification of bioactive molecules targeting atherogenesis at the level of ligand binding.
Martin
Catherine A
CA
MRC Clinical Sciences Centre, Imperial College, Hammersmith Hospital Campus, London, UK.
Longman
Emma
E
Wooding
Carol
C
Hoosdally
Sarah J
SJ
Ali
Saira
S
Aitman
Timothy J
TJ
Gutmann
Daniel A P
DA
Freemont
Paul S
PS
Byrne
Bernadette
B
Linton
Kenneth J
KJ
D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism; D018955:CD36 Antigens / Q000096:biosynthesis*; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity / Q000379:methods; D005786:Gene Expression Regulation; D006801:Humans; D007313:Insecta / Q000378:metabolism; D008024:Ligands; D008077:Lipoproteins, LDL / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051116:Receptors, Scavenger / Q000378:metabolism; D012995:Solubility
D018955:CD36 Antigens; D008024:Ligands; D008077:Lipoproteins, LDL; D051116:Receptors, Scavenger; D010100:Oxygen