>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
<0.10 EU per 1 μg of the protein by the LAL method.
Measured in a competitive binding assay. When human LDL is immobilized at 1 μg/mL (100 μL/well), Recombinant
Human LDL R inhibits 50% binding of Biotinylated Recombinant Human LDL R
(0.5 μg/mL) at the concentration range of 0.2-1.2 μg/mL.
Human embryonic kidney cell, HEK293-derived Ala22-Arg788 (Asp193Ala), with a C-terminal 6-His tag
When Human LDL is immobilized at 1 μg/mL (100 μL/well),Recombinant Human LDL R (Catalog # 9177-LD) inhibits the binding between HumanLDL and Biotinylated Recombinant Human LDL R. The ED50 for this effect is0.2-1.2 μg/mL.
Background: LDL R
The low density lipoprotein receptor (LDL R) is the founding member of the LDL R family of widely expressed cell surface scavenger receptors (1-5). Members of the family are endocytic receptors, but can also co-regulate adjacent cell-surface signaling molecules (3, 4). Many proteins in the LDL R family are cleaved by extracellular proteases to release soluble forms to the circulation, and many of these soluble forms are active (1, 6). Mature LDL R is a 120-160 kDa (depending on glycosylation) type I transmembrane glycoprotein that contains cysteine-rich complement-like repeats (class A LDL domains), calcium-binding EGF repeats, and beta -propeller structures (class B LDL repeats) in the extracellular domain (ECD) (1-7). A membrane-proximal Ser/Thr-rich region shows extensive O-linked glycosylation (4, 8). A cytoplasmic NPxY motif links the LDL R to clathrin pits for endocytosis, and binds to select adaptor proteins (1, 4, 8). The human LDL R ECD shares 78%, 76%, 81% and 82% aa sequence identity with mouse, rat, bovine, and porcine LDL R, respectively. LDL R is constitutively and widely expressed. Its class A LDL domains near the N-terminus bind apoB and apoE, the apolipoproteins of low- and very low-density lipoproteins (LDL and VLDL), respectively (1, 2, 4, 9). Hepatocyte LDL R is responsible for endocytosis and clearing of most plasma LDL cholesterol (2, 9). At the low pH of the endocytic vesicle, it dissociates, allowing degradation of LDL and recycling of LDL R to the cell surface (1, 4). Lack of LDL R expression or function causes familial hypercholesterolemia (FH) (4, 9, 10). The protease PCSK9 (proprotein convertase subtilisin/kexin type 9) can also cause increased plasma cholesterol by promoting LDL R degradation rather than recycling to the cell surface (10-12). Soluble forms of approximately 140 kDa and 28 kDa are reported to be released by phorbol esters or interferons, respectively (6, 7).
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Tavori, H. et al. (2013) Circulation 127:2403.
Low Density Lipoprotein Receptor
Entrez Gene IDs:
3949 (Human); 16835 (Mouse); 300438 (Rat)
FH; FHC; LDL R; LDL receptor; LDLCQ2; LDLR; low density lipoprotein receptor; low-density lipoprotein receptor class A domain-containing protein 3; low-density lipoprotein receptor
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