Apolipoprotein B100 (APOB100)

Apolipoprotein B100 is a protein that plays a role in metabolism. It is a form of low density lipoprotein (LDL). Apo-B levels correlate with the risk of coronary disease. The protein occurs in the plasma in 2 main isoforms, APOB48 and APOB100. The first is synthesized exclusively by the small intestine, the second by the liver. Both isoforms are coded by APOB and by a single mRNA transcript larger than 16 kb. . Apo-B100 is the major physiological ligand for the LDL receptor. Apo-B100 is a large monomeric protein, containing 4536 amino acids. Apo-B100 is synthesized in the liver and is required for the assembly of VLDL.

It does not interchange between lipoprotein particles, as do the other apolipoproteins, and it is found in IDL and LDL after the removal of the Apo-A, E and C. Apo-B48 is present in chylomicrons and their remnants. It is essential for the intestinal absorption of dietary lipids.