Anti-Apolipoprotein E (Apo E)

Apolipoprotein E (apo E), a component of lipoproteins produced by the liver and in circulating macrophages, plays a critical role in the reverse transport of cholesterol to the liver via the circulation. ApoE is also expressed in the brain and in response to injury in both the peripheral and central nervous systems. ApoE is a single polypeptide chain of 299 amino acids (~34kD) consisting of two independently folded functional domains. The C-terminal domain contains the major lipid-binding region. The N-terminal domain exists in the lipid-free state as a four-helix bundle of amphipathic a-helices and contains the LDLR-binding region (amino acids 136-150 in helix), which coincides with a heparin-binding site. Humans and mice lacking apoE cannot clear remnant lipoproteins from the plasma and are at increased risk for atherosclerosis. ApoE is a high-affinity ligand for the low density lipoprotein receptor (LDLR) family and for cell-surface heparan sulfate proteoglycans. Defective binding of apoE to receptors causes cholesterol-rich lipoprotein particles to accumulate in the plasma and is the mechanism of type III hyperlipoproteinemia, a genetic disorder characterized by elevated plasma cholesterol and triglyceride levels and accelerated coronary artery disease. In humans, apoE has three major isoforms: Apo E2 (Cys112, Cys158), Apo E3 (Cys112, Arg158), Apo E4 (Arg112, Arg158), products of alleles at a single gene locus. Although apoE4 is neither necessary nor sufficient to cause AD, inheritance of apoE4 is a significant risk factor for late onset AD, decreasing the age of onset and the duration of disease. Due primarily to this genetic linkage, the role of apoE in the pathogenesis AD is being actively studied. Applications: Western Blot: 1:1000 using Chemiluminescence technique.  Human ApoE is ~34kD (1)., ELISA: 1:10,000-1:100,000, using 50-100ng of control peptide/well. Storage and Stability: May be stored at 4°C for short-term only. For long-term storage, store at -20°C. Aliquots are stable for at least 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.