title: Essential role of cytoplasmic sequences for cell-surface sorting of the lectin-like oxidized LDL receptor-1 (LOX-1).
abstract: Lectin-like oxidized LDL receptor-1 (LOX-1) is an oxidized low-density lipoprotein (OxLDL) receptor found in endothelial cells and a member of the natural killer (NK) receptor gene complex. Here, we demonstrate that the ability of LOX-1 binding to OxLDL distinguishes it from other NK receptors. Domain swapping of the lectin-like domain between LOX-1 and the NK cell receptors CD94, NKG2D, and LY-49A demonstrated the crucial role of this domain for recognition of OxLDL by LOX-1, but not for the correct cell-surface sorting of LOX-1. Using LOX-1 GFP fusion constructs, we find that the combination of cytoplasmic and transmembrane domains of LOX-1 is sufficient to target the chimeric protein to the cell-surface. Using N-terminal deletions we determined that the correct cell-surface localization is dependent on a positively charged motif present in the cytosolic juxtamembrane region of LOX-1. Furthermore, the extracellular localization of the LOX-1 C-terminus is disrupted when we mutated the cytoplasmic basic amino acids, Lys-22, Lys-23 and Lys-25 to Glu. Collectively, these results indicate that the N-terminal cytoplasmic domain of LOX-1 determines the correct expression of the lectin domain on the cell-surface.
authors.affiliation: Department of Vascular Physiology, National Cardiovascular Center Research Institute, Suita, Osaka, Japan.
authors.forename: Mingyi
authors.initials: M
authors.lastname: Chen
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sawamura
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D024361:Amino Acids, Basic / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D017124:Conserved Sequence; D003593:Cytoplasm / Q000737:chemistry*; D004252:DNA Mutational Analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000166:cytology; D019084:Fluorescent Antibody Technique, Indirect; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D037102:Lectins / Q000737:chemistry / Q000378:metabolism*; D037181:Lectins, C-Type / Q000737:chemistry / Q000378:metabolism; D008567:Membranes, Artificial; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D051920:NK Cell Lectin-Like Receptor Subfamily D; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011973:Receptors, LDL / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051131:Receptors, Oxidized LDL; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012015:Reference Standards; D051127:Scavenger Receptors, Class E; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
chemical_list: D024361:Amino Acids, Basic; D015703:Antigens, CD; C497869:KLRD1 protein, human; C497870:Klrd1 protein, mouse; D037102:Lectins; D037181:Lectins, C-Type; D008567:Membranes, Artificial; D051920:NK Cell Lectin-Like Receptor Subfamily D; C495137:OLR1 protein, human; C495138:Olr1 protein, mouse; D011973:Receptors, LDL; D051131:Receptors, Oxidized LDL; D011993:Recombinant Fusion Proteins; D051127:Scavenger Receptors, Class E; D049452:Green Fluorescent Proteins