Scavenger receptor family proteins: roles for atherosclerosis, host defence and disorders of the central nervous system

In this review, we summarize the structure and function of the scavenger receptor family of proteins including class A (type I and II macrophage scavenger receptors, MARCO), class B (CD36, scavenger receptor class BI), mucinlike (CD68/macrosialin. dSR-CI) and endothelial (LOX-1) receptors. Two motifs have been identified as ligand-binding domains: a charged collagen structure of type I and II receptors, and an immunodominant domain of CD36. These structures can recognize a wide range of negatively charged macromolecules, including oxidized low-density lipoproteins, damaged or apoptotic cells, and pathogenic microorganisms. After binding, these ligands can be either internalized by endocytosis or phagocytosis, or remain at the cell surface and mediate adhesion or lipid transfer through caveolae. Under physiological conditions, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, and they play a role in host defence. In pathological states, they mediate the recruitment, activation and transformation of macrophages and other cells which may be related to the development of atherosclerosis and to disorders caused by the accumulation of denatured materials, such as Alzheimer's disease.