Major structural Proteins of triacylglycerol-rich Lipoproteins. There are two Forms, Apolipoprotein B-100 and Apolipoprotein B-48, both derived from a single Gene. ApoB-100 expressed in the liver is found in Low-Density Lipoproteins (Lipoproteins, LDL; Lipoproteins, VLDL). ApoB-48 expressed in the Intestine is found in Chylomicrons. They are important in the biosynthesis, transport, and Metabolism of triacylglycerol-rich Lipoproteins. Plasma Apo-B levels are high in atherosclerotic Patients but non-detectable in Abetalipoproteinemia.