出版社：American Society for Biochemistry and Molecular Biology
摘要：Scavenger receptor class B type I (SR-BI) has been established as the primary mediator of the selective transfer of lipids from HDL to mammalian cells. In addition to its role in cholesterol metabolism, SR-BI has been shown to bind apoptotic cells and thus could in theory also function as a scavenger receptor. We now show that SR-BI binds oxidized LDL (OxLDL) with high affinity ( Kd of 4.0 ± 0.5 μg/ml) and mediates internalization and degradation to an extent comparable to that of other scavenger receptors, when normalized to binding activity. The best competitors for OxLDL binding to SR-BI were oxidized lipoproteins, whereas native or acetylated lipoproteins only competed for a small fraction of OxLDL binding. Both the isolated lipids and the isolated protein from OxLDL bound with high affinity to SR-BI and showed partial reciprocal competition. Monoclonal antibody EO6, an antibody against oxidized phospholipids, and 1-palmitoyl-2-(5-oxovaleroyl) phosphatidylcholine (POVPC) both competed effectively with intact OxLDL and with isolated lipids from OxLDL for SR-BI binding. Together, these results demonstrate a potential function of SR-BI, in addition to its role in selective uptake of lipids, to mediate internalization of OxLDL by macrophages and suggest a central role for oxidized phospholipids in this process. —Gillotte-Taylor, K., A. Boullier, J. L. Witztum, D. Steinberg, and O. Quehenberger. Scavenger receptor class B type I as a receptor for oxidized low density lipoprotein. J. Lipid Res. 2001. 42: 1474–1482.
