This pathway shows genetic disorders related to lipoprotein metabolism. Two plasmalipoproteins, LDL and HDL, and one plasma lipid, triglyceride (TG), play an important role in this pathway. Hydrophobic lipids and fat-soluble vitamins are normally transported to the site of their uptake by transporters called lipoproteins, and any deregulation of the plasma concentrations of these proteins can cause dyslipidemias. Disorders resulting from an enzyme deficiency are highlighted in pink. More details on the composition of the various lipoproteins in this pathway are visualised in [https://www.wikipathways.org/index.php/Pathway:WP3601]. This pathway was inspired by Chapter 43 of the book of Blau (ISBN 3642403360 (978-3642403361)). e64 "Oxysterols are oxygenated derivatives of cholesterol or its sterol precursors, e.g. 7-dehydrocholesterol (7-DHC) or desmosterol" [ PubMed 27068984]. See https://www.wikipathways.org/index.php/Pathway:WP4346 for mouse version (Human will be created at some point). a5e AKA SCARB1; Receptor for HDL, mediating selective uptake of cholesteryl ether and HDL-dependent cholesterol efflux. e62 AKA Lecithin-cholesterol acyl transferase AKA Low density lipoprotein receptor adapter protein 1; ARH1 "Adapter protein (clathrin-associated sorting protein (CLASP)) required for efficient endocytosis of the LDL receptor (LDLR) in polarized cells such as hepatocytes and lymphocytes, but not in non-polarized cells (fibroblasts). May be required for LDL binding and internalization but not for receptor clustering in coated pits. May facilitate the endocytocis of LDLR and LDLR-LDL complexes from coated pits by stabilizing the interaction between the receptor and the structural components of the pits. May also be involved in the internalization of other LDLR family members." [https://www.uniprot.org/uniprot/Q5SW96] a69 EC 3.1.1.3 EC 3.1.1.3 aka LIPC caa "Catalyzes the transport of triglyceride, cholesteryl ester, and phospholipid between phospholipid surfaces. Required for the secretion of plasma lipoproteins that contain apolipoprotein B." [https://www.uniprot.org/uniprot/P55157] AKA Apolipoprotein C2; cofactor for lipoprotein lipase (LPL) enzyme. ca1 "The chylomicron remnant receptor accepts apoE as a ligand. Chylomicron remnants are removed from the circulation exclusively by the liver, probably because these large complexes can penetrate the unique sinusoidal vascular space. The multifunctional, α2-macroglobulin/LDL receptor-related protein (LRP) is the chylomicron remnant receptor" [https://doi.org/10.1016/B978-1-4160-6189-2.00072-X] "Apolipoprotein B(apo B) occurs in the plasma in 2 main isoforms, ApoB48 and ApoB100. ApoB48 is generated when a stop codon (UAA) is created by RNA editing. As a result of the RNA editing, ApoB48 and ApoB100 share a common N-terminal sequence, but ApoB48 lacks ApoB100's C-terminal LDL receptor binding region. In fact, ApoB48 is so called because it constitutes 48% of the sequence for ApoB100. ApoB 48 is a unique protein to chylomicrons from the small intestine. After most of the lipids in the chylomicron have been absorbed, ApoB48 returns to the liver as part of the chylomicron remnant, where it is endocytosed and degraded." [https://en.wikipedia.org/wiki/Apolipoprotein_B] Synthesized in small intestine. Transcript ID: ENST00000233242.4 AKA APo E, a ligand for receptor mediated endocytosis. Very low-density lipoprotein (VLDL) is one of the two main TG (triglyceride or triacylglycerol) carrying lipoproteins, which are spheroidal macromolecular complexes responsible for transporting lipids through plasma. "Apoprotein B100 (ApoB-100) is embedded in the outer phospholipid layer of LDL particles." [https://en.wikipedia.org/wiki/LDL_receptor] Synthesized in liver. "Apolipoprotein B(apo B) occurs in the plasma in 2 main isoforms, ApoB48 and ApoB100. ApoB48 is generated when a stop codon (UAA) is created by RNA editing. As a result of the RNA editing, ApoB48 and ApoB100 share a common N-terminal sequence, but ApoB48 lacks ApoB100's C-terminal LDL receptor binding region. In fact, ApoB48 is so called because it constitutes 48% of the sequence for ApoB100. ApoB 48 is a unique protein to chylomicrons from the small intestine. After most of the lipids in the chylomicron have been absorbed, ApoB48 returns to the liver as part of the chylomicron remnant, where it is endocytosed and degraded." [https://en.wikipedia.org/wiki/Apolipoprotein_B] Synthesized in small intestine. AKA APo E, a ligand for receptor mediated endocytosis. AKA Apo A-I; activator of lecithin-cholesterol acyl transferase (LCAT). AKA Apolipoprotein A-II AKA Apo A-I; activator of lecithin-cholesterol acyl transferase (LCAT). Itermediate-density lipoprotein (IDL), physiologically a short lived species, containd around equimolar amounts of cholesterol and Triglycerides (TG). "Apoprotein B100 (ApoB-100) is embedded in the outer phospholipid layer of LDL particles." [https://en.wikipedia.org/wiki/LDL_receptor] Synthesized in liver. Low-density lipoprotein (LDL) is one of the two main cholesterol carrying lipoproteins, which are spheroidal macromolecular complexes responsible for transporting lipids through plasma. "Apoprotein B100 (ApoB-100) is embedded in the outer phospholipid layer of LDL particles." [https://en.wikipedia.org/wiki/LDL_receptor] Synthesized in liver. AKA Apolipoprotein C2; cofactor for lipoprotein lipase (LPL) enzyme. AKA APo E, a ligand for receptor mediated endocytosis. AKA APo E, a ligand for receptor mediated endocytosis. 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