Lipolysis and Lipid Mobilization in Human Adipose Tissue
Adipose tissue is the body’s largest energy reservoir. Energy is stored in fat cells as triacylglycerols (TG). Factors that control the storage and mobilization of TG in adipocytes are important regulators of fat accumulation in various fat areas (1). The major source for adipocyte TG comes from chylomicrons and very low density lipoproteins (VLDL). TG in the lipoprotein particles are hydrolyzed by lipoprotein lipase (LPL) located on the capillary walls of adipose tissue so that nonesteriﬁed fatty acids (NEFA) and monoacylglycerol are formed. NEFA are probably taken up by the fat cell through passive and active transport. Indeed, speciﬁc NEFA-transporting proteins have been described (2-4). Once taken up by the fat cells, NEFA are esteriﬁed to TG. The circulating albumin-bound NEFA can also be taken up by the fat cells and esteriﬁed to TG.