Triacylglycerol Movement in Enterocytes

Abstract

This chapter covers the movement of triacylglycerols (TGs) within enterocytes. Relatively little is known about how TG vectorially transits the intestinal absorptive cell compared to other aspects of intestinal cellular function. Intracellular TG movement is important because in humans, the intestine must absorb 100 to 150 gm of fat per day on a typical Western diet, which, if inefficiently done, may result in steatorrhea, the excessive excretion of fat in the stool, and may also lead to fat-soluble vitamin deficiencies. Normally, the end result of the complex process of lipid absorption is the export of TG containing long-chain fatty acids (FA) into the lymph in a unique, specialized lipoprotein particle, the chylomicron (Green and Glickman, 1981) and a slightly more dense particle, the very low density lipoprotein (VLDL, Ockner et al., 1969b; Tso et al, 1987). More recent studies have begun to shed some light on how TG moves from its site of synthesis in the endoplasmic reticulum (ER) to its exit site at the basolateral membrane of the enterocyte as shown schematically in Fig. 1.