DNA encoding human apoB48R: a monocyte-macrophage apolipoprotein B48 receptor gene and protein

摘要

The present invention provides an isolated DNA molecule that codes for a cell-surface binding protein in human monocytes and macrophages. In addition, an amino acid sequence derived from the nucleotide sequence is provided. The newly-identified cell-surface binding protein described herein is instrumental in the apoB-mediated cellular uptake of plasma chylomicrons and remnants and hypertriglyceridemic triglyceride-rich lipoproteins in an ApoE- and lipoprotein lipase- and heparin sulfate proteoglycan-independent pathway. The new human macrophage receptor has been cloned and uniquely, binds TGRLP via apolipoprotein B48, the marker of dietary TGRLP (apoB48R). This process rapidly converts macrophages and apoB48R-transfected Chinese hamster ovary cells in vitro into lipid-filled "foam cells," hallmarks of atherosclerotic lesions. The apoB48R cDNA (3744 bp) encodes a novel protein with no known homologs. Its ~3.8 kb mRNA is expressed primarily by reticuloendothelial cells. Immunohistochemical studies indicate that foam cells of human atherosclerotic lesions express the apoB48R.