Résumé
The scavenger receptor (SRA or RPA) belongs to a wide family of receptor proteins. The classification is based on sequence homologies and structural similarities; nevertheless, it has been useful to group them on the basis of ligand specificity. The SRA was first identified as a receptor for modified low-density lipoproteins, where such modification permits to regulate the uptake of modified LDL by macrophages leading to a massive cholesterol accumulation. Moreover, SRA facilitates the clearance by phagocytic cells of microbial pathogens and senescent cells. SRA is a transmembrane glycoprotein that exists as a trimer comprised of a cystein-linker dimer and a non-covalently bound monomer. SRA has an a-helical coiled coil domain, which is essential for both trimer formation and acid-dependent ligand dissociation. It also contains a collagenous domain, essential for ligand binding. The majority of these ligands are polyanionic molecules, such as the A beta-peptide, important in the development of Alzheimer's disease. Present findings including our own consider that binding of these peptides to SRA activates an inflammatory response with the production of oxidative stress.