Remnant receptor (Apo-E) Found in the liver only. The major determinant of LDL concentration in plasma is the number/activity of LDL receptors. Next, MTP lipidates the chylomicron structural protein, Apo B-48. Unlike chylomicrons, the VLDL remnants may be further metabolized to become LDL. Recognizes Chylomicron Remnants and Apo-E Rich HDL receptors. The ApO E has a high affinity for LDL receptors and LDL related proteins. Defective chylomicron-remnant removal but normal LDL clearance in the heterozygote WHHL corresponded to elevated concentrations of plasma triacylglycerol and normal concentrations of plasma cholesterol. Uptake of oxidized or chemically modified LDL-Particles by Monocytes in circulation or Macrophages in tissues (these are not recognised by LDL receptor). Let’s compare Chylomicrons with other terms. hypercholesterolaemia (FH), remnant receptor & triglycerides. The recognition of chylomicron remnants by the hepatic remnant receptor also requires apoE. Like chylomicron remnants, the triglyceride-poor VLDL remnants may reenter the liver. The chylomicron remnant is picked up by hepatocytes through the apoE receptor; thus, dietary cholesterol, as well as any remaining triglyceride, is released in the hepatocyte. Remnants derived from VLDL are found mainly in the IDL (d = 1.006–1.019 g/mL) range after ultracentrifugation, although some are also present in the VLDL density range (d < 1.006 g/mL). Scavenger receptor. The remnant chylomicron contains small levels of TAGs and cholesterol. Interaction of chylomicron remnants with the LDL receptor-related protein, or another endocytic receptor with similar properties, occurs slowly, requiring modification of surface-bound chylomicron remnants, and serves as a backup mechanism that is utilized primarily when LDL receptors are deficient or down-regulated. Once triglyceride stores are distributed, the chylomicron returns APOC2 to the HDL (but keeps APOE), and, thus, becomes a chylomicron remnant, now only 30–50 nm. Receptor binding. APOB48 and APOE are important to identify the chylomicron remnant in the liver for endocytosis and breakdown. VLDL (Very Low-Density Lipoprotein) APOB48 and APOE are important for the identification of chylomicron remnants in the liver due to endocytosis and degradation. Chylomicron remnants can also remain sequestered in the space of Disse by binding of apoE to heparan sulfate proteoglycans and/or binding of apoB-48 to hepatic lipase. Chylomicron remnant. Chylomicron remnant clearance is mediated by the action of lipoprotein The clearance of chylomicron remnants in humans is a complex mechanism which has not been fully elucidated. The lipidated Apo B-48 is now termed a chylomicron, and it is composed primarily of dietary triglycerides. Chylomicron Remnant: When the triglyceride reserve consumes (distributed), it converts APOC2 back to HDL (which APOE retains), leaving chylomicrons remnants of only 20-50 nm. For competition studies, a lO-fold excess of un labelJed chylomicron remnants or LOL receptor antibody (3,7JJg/mL protein) was included in the incubation buffer containing gold--chylomicron remnant conjugates. It has ApO B48 and ApO E, but the ApO C2 is returned to HDL. Previously, it was shown that canine HDL c was a competitive inhibitor of chylomicron remnants for uptake by the perfused rat liver , and in addition to their ability to bind with high affinity to the LDL receptor (1, 49), HDL c have now been demonstrated to bind to … Delivers cholesterol to liver and it is not regulated. What is the point of ApO E? Introduction Chylomicron remnants are potentially atherogenic lipoproteins [1]4]. 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