Apo CII is a cofactor for lipoprotein lipase (LPL), an enzyme that hydrolyses the triglycerides in the triglyceride-rich lipoproteins, leading to the formation of partially triglyceride-depleted chylomicron remnants. Free fatty acids that are liberated by the action of LPL are taken up and re-esterified for storage as triglycerides in adipose tissue (Fig. 6.6). The chylomicron remnants then lose apo CII and acquire apo E, which is shuttled to and from HDL (see below). Apo E mediates the binding of chylomicron remnants to chylomicron remnant receptors on the liver. The remnants then deliver cholesterol to the hepatocyte for synthesis of bile acid and very low-density lipoproteins (VLDLs).
