apolipoprotein E, a protein component of lipoprotein complexes found in very-low-density lipoprotein (VLDL), high-density lipoprotein, chylomicrons, and chylomicron remnants. It facilitates hepatic uptake of chylomicron and VLDL remnants and is elevated in patients with type III hyperlipoproteinemia. One form of apolipoprotein E has been linked to Alzheimer’s disease.
