MSR1 (SCARA1, SR-A) binds oxidized and acetylated low density lipid (LDL) particles ((Brown et al. 1980), Haberland et al 1984, Gough et al. 1998, Yang et al. 2011), apolipoproteins A-I and E (human and mouse, Neyen et al. 2009), lysophosphatidylcholine from apoptotic cells (mouse, Sakai et al. 1996), phosphatidylinositol and phosphatidylserine (mouse, Nishikawa et al. 1990). MSR1 binds activated B-lymphocytes (human, Yokota et al. 1998), calreticulin and gp96 (mouse, Berwin et al. 2003). MSR1 binds bacterial products (E.coli, Neisseria meningitides, Staphylococcus aureus) (mouse, Peiser et al. 2006), Lipopolysaccharide (LPS) (mouse and bovine, Hampton et al. 1991), Lipoteichoic acid (LTA) and Gram-positive bacteria (bovine, Dunne et al. 1994), Adenovirus 5 (Haisma et al. 2009). MSR1 binds polysaccharides (carrageenan, dextran sulphate, fucoidan) (Brown et al. 1980, Krieger et al. 1992), extracellular matrix proteoglycans, biglycan and decorin (mouse, Santiago-Garcia et al. 2003). MSR1 binds extracellular matrix molecules, including denatured type I and III collagen, as well as glycated collagen IV (human and mouse and bovine, el Khoury et al. 1994, Gowen et al. 2000, Gowen et al. 2001), beta-amyloid fibrils (human and mouse, El Khoury et al. 1996), maleyl-BSA and advanced glycation end-product modified (AGE)-BSA (bovine, Brown et al. 1980, Araki et al. 1995). MSR1 binds polynucleotides (polyI, polyG) (bovine, Brown et al. 1980, Pearson et al. 1993, Mielewczyk et al. 1996), double-stranded RNA (Limmon et al. 2008, DeWitte-Orr et al. 2010). MSR1 interacts with the modified apoB-100 component of LDL (Parthasarathy et al. 1987) and with the lipid part of LDL (Terpstra et al. 1998). MSR1 is expressed most strongly on macrophages and can also be detected on endothelial cells and smooth muscle cells.