Lipids that are resynthesized in the ER of the enterocytes leave the enterocyte by exocytosis as chylomicrons. Chylomicrons are large TAG-rich spherical particles that consist of large amounts of triglycerides at the core and apolipoproteins as the surface protein component. Apolipoprotein B (apoB) plays a critical role in the assembly of the triglyceride -rich lipoproteins. ApoB are large lipoprotein particles that contain a number of different lipid binding proteins. ApoB-100 and ApoB-48 are two large, hydrophobic, monomeric proteins. The major protein component of ApoB-100 is LDLs, which deliver cholesterol to peripheral tissues. ApoB-100 is the protein that attaches LDL to its cell surface receptor; apoB-48 lacks this property. ApoB-48
