The hydrophobic tunnel present in LOX-1 is essential for oxidized LDL recognition and binding.
Lectin-like oxidized LDL (ox-LDL) receptor-1 (LOX-1) is a type-II transmembrane protein that belongs to the C-type lectin family of molecules. LOX-1 acts as a cell surface endocytosis receptor and mediates the recognition and internalization of ox-LDL by vascular endothelial cells. Internalization of ox-LDL by LOX-1 results in a number of pro-atherogenic cellular responses implicated in the development and progression of atherosclerosis. In an effort to elucidate the functional domains responsible for the binding of ox-LDL to the receptor, a series of site-directed mutants were designed using computer modeling and X-ray crystallography to study the functional role of the hydrophobic tunnel present in the LOX-1 receptor. The isoleucine residue (I(149)) sitting at the gate of the channel was replaced by phenylalanine, tyrosine, or glutamic acid to occlude the channel opening and restrict the docking of ligands to test its functional role in the binding of ox-LDL. The synthesis, intracellular processing, and cellular distribution of all mutants were identical to those of wild type, whereas there was a marked decrease in the ability of the mutants to bind ox-LDL. These studies suggest that the central hydrophobic tunnel that extends through the entire LOX-1 molecule is a key functional domain of the receptor and is critical for the recognition of modified LDL.
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340. Electronic address: omar.l.francone@pfizer.com.
Omar L
OL
Francone
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Meihua
M
Tu
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Lori J
LJ
Royer
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Jian
J
Zhu
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Kimberly
K
Stevens
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Joseph J
JJ
Oleynek
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Zhiwu
Z
Lin
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Lorraine
L
Shelley
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Thomas
T
Sand
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Yi
Y
Luo
Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
Christopher D
CD
Kane
D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051127:Scavenger Receptors, Class E / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D011994:Recombinant Proteins; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein