ApoB48R (apolipoprotein B48 receptor), also known as apolipoprotein B-100 receptor, is a 1,088 amino acid protein that functions as a macrophage receptor by binding to apoB of dietary triglyceride-rich lipoproteins or to a similar apoB-like domain in hypertriglyceridemic very low density lipoprotein (HTG-VLDL). ApoB48R may contribute necessary lipids, lipid-soluble vitamins and other nutrients to reticuloendothelial cells. Significantly elevated plasma triglyceride levels may cause apoB48R to be a factor in foam cell formation, endothelial dysfunction and atherothrombogenesis. ApoB48R also mediates the swift, high-affinity uptake of chylomicrons, HTG-VLDL and trypsinized VLDL lacking apoE in in vitro macrophages. Conserved in chimpanzee, dog, cow, mouse and rat, apoB48R is ubiquitously expressed in all tissues, except skeletal muscle, with high expression in lung and placenta, and low expression in brain and heart. ApoB48R is encoded by a gene that maps to human chromosome 16p11.2 and exists as three alternatively spliced isoforms.