Apolipoprotein E Rabbit Polyclonal Antibody

Function

Apolipoprotein-E (apoE) is a protein component of plasma lipoproteins. Three common ApoE alleles have been identified: ApoE2, ApoE3, and ApoE4. The corresponding three major isoforms, E2, E3, and E4, are recognized according to their relative position after isoelectric focusing. ApoE mediates the binding, internalization, and catabolism of lipoprotein particles. It can serve as a ligand for the LDL (Apo B/E) receptor and for the specific Apo-E receptor (chylomicron remnant) of hepatic tissues. Defects in Apolipoprotein E result in familial dysbetalipoproteinemia, or type III hyperlipoproteinemia (HLP III), in which increased plasma cholesterol and triglycerides are the consequence of impaired clearance of chylomicron and VLDL remnants.

Background References

1. "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."The MGC Project Team Genome Res. 14:2121-2127(2004)

2. "Glycation of apolipoprotein E impairs its binding to heparin: identification of the major glycation site."Shuvaev V.V., Fujii J., Kawasaki Y., Itoh H., Hamaoka R., Barbier A., Ziegler O., Siest G., Taniguchi N.Biochim. Biophys. Acta 1454:296-308(1999)

Sequence Similarity

Belongs to the apolipoprotein A1/A4/E family.

Tissue Specificity

Produced by several tissues and cell types and mainly found associated with lipid particles in the plasma, the interstitial fluid and lymph. Mainly synthesized by liver hepatocytes. Significant quantities are also produced in brain, mainly by astrocytes and glial cells in the cerebral cortex, but also by neurons in frontal cortex and hippocampus. It is also expressed by cells of the peripheral nervous system. Also expressed by adrenal gland, testis, ovary, skin, kidney, spleen and adipose tissue and macrophages in various tissues.

Post-translational Modification

APOE exists as multiple glycosylated and sialylated glycoforms within cells and in plasma. The extent of glycosylation and sialylation are tissue and context specific. Plasma APOE undergoes desialylation and is less glycosylated and sialylated than the cellular form. Glycosylation is not required for proper expression and secretion. O-glycosylated with core 1 or possibly core 8 glycans. Thr-307 and Ser-314 are minor glycosylation sites compared to Ser-308.; Glycated in plasma VLDL of normal subjects, and of hyperglycemic diabetic patients at a higher level (2-3 fold).; Phosphorylated by FAM20C in the extracellular medium.; Undergoes C-terminal proteolytic processing in neurons. C-terminally truncated APOE has a tendency to form neurotoxic intracellular neurofibrillary tangle-like inclusions in neurons.

Subcellular Location

Secreted.

UNIPROT

SwissProt: P02649 Human

Synonyms