Search results for LDLR

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Identifier: R-HSA-8866427
Species: Homo sapiens
The steps involved in proprotein convertase PCSK9-induced degradation of VLDLR are described here (Poirier et al. 2008). The rate of this catabolic process plays a clinically significant role in determining the efficiency of lipoprotein clearance from the blood.
Identifier: R-HSA-9031525
Species: Homo sapiens
Liver X receptors NR1H3 (LXR alpha) and NR1H2 (LXR beta) are sterol-responsive transcription factors that become activated upon the engagement with their cognate oxysterol ligands. Ligand-activated NR1H2 & NR1H3 induce a genetic program aimed at reducing the cellular sterol load by limiting cholesterol uptake, attenuating cholesterol biosynthesis and promoting cholesterol efflux. This Reactome module describes the NR1H2 & NR1H3-regulated expression of MYLIP (IDOL) gene, an E3 ubiquitin ligase, that triggers ubiquitination of the low-density lipoprotein receptor (LDLR) on its cytoplasmic domain, targeting it for degradation and thereby limiting cholesterol uptake (Zelcer N et al. 2009; Zhang L et al. 2012).
Identifier: R-HSA-8964043
Species: Homo sapiens
Circulating chylomicrons acquire molecules of apolipoproteins C and E and through interaction with endothelial lipases lose a large fraction of their triacylglycerol. These changes convert them to chylomicron remnants which bind to LDL receptors, primarily on the surfaces of liver cells, clearing them from the circulation (Redgrave 2004).
Most very-low-density lipoproteins (VLDL) are converted to low-density lipoproteins (LDL) (VLDL remodeling pathway). A small fraction are taken up by VLDL receptors on extrahepatic cells, as annotated here. Clearance of LDL from the blood involves binding to LDL receptors associated with coated pits at the cell surface, forming complexes that are internalized and passed via clathrin-coated vesicles to endosomes, where they dissociate. The LDL particles move into lysosomes and are degraded while the LDL receptors are returned to the cell surface. This process occurs in most cell types but is especially prominent in hepatocytes. It plays a major role in returning cholesterol from peripheral tissues to the liver (Hobbs et al. 1990).
Clearance of circulating HDL particles involves particle binding to cell-surface SR-BI receptors, particle disassembly with rlease of pre-beta HDL (Silver & Tall 2001), and uptake of the latter mediated by cell-surface CUBN:AMN complex (Kozyraki et al. 1999).
VLDLR internalization plays a clinically significant role in determining the efficiency of lipoprotein clearance from the blood (Poirier et al. 2008).
Identifier: R-HSA-8964026
Species: Homo sapiens
Circulating chylomicrons acquire molecules of apolipoproteins C and E and through interaction with endothelial lipases lose a large fraction of their triacylglycerol. These changes convert them to chylomicron remnants which bind to LDL receptors, primarily on the surfaces of liver cells, clearing them from the circulation.
This binding and clearance process involves several steps and requires the presence of heparan sulfate proteoglycan (HSPG)-associated hepatic lipase (HL). The molecular details of LDLR binding, and of the following steps of remnant endocytosis, are inferred from those of the coorresponding step of LDLR-mediated low-density lipoprotein (LDL) endocytosis (Redgrave 2004).
Identifier: R-HSA-8964041
Species: Homo sapiens
LDL (low density lipoproteins) are complexes of a single molecule of apoprotein B-100 (apoB-100) non-covalently associated with triacylglycerol, free cholesterol, cholesterol esters, and phospholipids. CETP (cholesterol ester transfer protein) complexed with cholesterol esters interacts with an LDL (low density lipoprotein) particle, acquiring triacylglycerol molecules and donating cholesterol ester to the LDL (Swenson et al. 1988; Morton & Zilversmit 1983), a key step in the transport of tissue cholesterol to the liver.
As an alternative to LDLR-mediated uptake and degradation, a LDL particle can bind a single molecule of LPA (apolipoprotein A), forming a Lp(a) lipoprotein particle (Lobentanz et al. 1998).
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