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. 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 ) .
