Belongs to the apolipoprotein C4 family.
May participate in lipoprotein metabolism.
APOE exists as multiple glycosylated and sialylated glycoforms within cells and in plasma. The extent of glycosylation and sialylation are tissue and context specific.
APOE is an apolipoprotein, a protein associating with lipid particles, that mainly functions in lipoprotein-mediated lipid transport between organs via the plasma and interstitial fluids. APOE is a core component of plasma lipoproteins and is involved in their production, conversion and clearance. Apolipoproteins are amphipathic molecules that interact both with lipids of the lipoprotein particle core and the aqueous environment of the plasma. As such, APOE associates with chylomicrons, chylomicron remnants, very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL) but shows a preferential binding to high-density lipoproteins (HDL). It also binds a wide range of cellular receptors including the LDL receptor/LDLR and the very low-density lipoprotein receptor/VLDLR that mediate the cellular uptake of the APOE-containing lipoprotein particles. Finally, APOE has also a heparin-binding activity and binds heparan-sulfate proteoglycans on the surface of cells, a property that supports the capture and the receptor-mediated uptake of APOE-containing lipoproteins by cells.
Belongs to the apolipoprotein A1/A4/E family.
Homotetramer. May interact with ABCA1; functionally associated with ABCA1 in the biogenesis of HDLs. May interact with APP/A4 amyloid-beta peptide; the interaction is extremely stable in vitro but its physiological significance is unclear. May interact with MAPT. May interact with MAP2. In the cerebrospinal fluid, interacts with secreted SORL1. Interacts with PMEL; this allows the loading of PMEL luminal fragment on ILVs to induce fibril nucleation.
Phosphorylated by FAM20C in the extracellular medium.
Serves as a reserve supply of oxygen and facilitates the movement of oxygen within muscles.
Belongs to the PTEN phosphatase protein family.