Description_x000D_ Biochem/physiol Actions_x000D_ Apo-B levels correlate with the risk of coronary disease. Apo-B exists in human plasma in two isoforms, Apo-B48 and Apo-B100. Apo-B100 is the major physiological ligand for the LDL receptor. Apo-B100 is a large monomeric protein, containing 4563 amino acids (MW 515 kDa). 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._x000D_ Apo-B48 is synthesized in the small intestine. It comprises approximately half of the N-terminal region of Apo-B100 and is the result of posttranscriptional mRNA editing by a stop codon in the intestine not found in the liver. The concentration of Apo-B in normal plasma is ~90 mg/dl._x000D_ Physical form_x000D_ Lyophilized from buffer containing 10 mM sodium deoxycholate, 0.05 M sodium carbonate and 0.05 M sodium chloride, pH 10.0_x000D_ Preparation Note_x000D_ Delipidated with sodium deoxycholate.