Lipids triacylglycerol synthesis

VLDLs are produced in the liver (Figure 18.17). They are composed predominantly of triacylglycerol, and their function is to carry this lipid from the liver to the peripheral tissues. There, the triacylglycerol is degraded by lipoprotein lipase, as discussed for chylomicrons (see p. 226). [Note "Fatty liver" (hepatic steatosis) occurs in conditions in which there is an imbalance between hepatic triacylglycerol synthesis and the secretion of VLDL. Such conditions include obesity, uncontrolled diabetes mellitus, and chronic ethanol ingestion.]... 

Yeh, Y.Y. and Yeh, S.M. (1994) Garlic reduces plasma lipids by inhibiting hepatic cholesterol and triacylglycerol synthesis. Lipids. 29 189-193. 

See also Adipocytes, Fat Absorption and Transport, Bile Salts and Emulsion of Fats, Mobilization of Stored Fat, Energy Storage, Triacylglycerol Synthesis, Action of Insulin, Lipids... 

See also Energy Storage, Triacylglycerol Synthesis, Biochemistry of Obesity, Lipids... 

Lung, S.C. R.J. Weselake. Diacylglycerol acyltransferase a key mediator of plant triacylglycerol synthesis. Lipids 2QQ6, 41, 1073-1088. 

T3 has an amplifying or facilitatory effect on the lipolytic action of epinephrine on the fat cell. Yet thyroid hormone has a bipolar effect on lipid storage, because it increases the availability of glucose to the fat cell, which serves as a precursor for fatty acid and glycerol 3-phosphate synthesis. The major determinant of the rate of lipogenesis, however, is not T3, but rather the amount of glucose and insulin available to the adipocyte for triacylglycerol synthesis. 

Lacey DJ and Hills MJ (1995) Identification of a low density membrane fraction involved in storage triacylglycerol synthesis. In Plant Lipid Metabolism, Kader J-C and Mazliak P eds pp 482-485 Lacey, D.J. and Hills, M.J. (1996) Heterogeneity of the endoplasmic reticulum with respect to lipid synthesis in developing seeds of Brassica napus L. Plantar In Press... 

Sakaki T, Ohnishi J, Kondo N, Yamada M. Polar and neutral lipid changes in spinach leaves with ozone fumigation Triacylglycerol synthesis from polar lipids. Plant Cell Physiol 1985 26 253-262. 

He, X., Chen, G.Q., Lin, J.-T, McKeon, T.A., 2006. Diacylglycerol acyltransferase activity and triacylglycerol synthesis in germinating castor seed cotyledons. Lipids 41, 281-285. 

Martin, B.A., Wilson, R.F., 1984. Subcellular localization of triacylglycerol synthesis in spinach leaves. Lipids 19, 117-121. 

Increased lipid synthesis/inhibi-tion of lipolysis Activation of lipoprotein lipase (LPL)/induc-tion of fatty acid synthase (FAS)/inactivation of hormone sensitive lipase (HSL) Facilitated uptake of fatty acids by LPL-dependent hydrolysis of triacylglycerol from circulating lipoproteins. Increased lipid synthesis through Akt-mediated FAS-expression. Inhibition of lipolysis by preventing cAMP-dependent activation of HSL (insulin-dependent activation of phosphodiesterases )... 

The source of long-chain fatty acids is either dietary lipid or de novo synthesis from acetyi-CoA derived from carbohydrate. Fatty acids may be oxidized to acetyl-CoA (P-oxidation) or esterifred with glycerol, forming triacylglycerol (fat) as the body s main fuel reserve. 

The second type of fatty liver is usually due to a metabolic block in the production of plasma lipoproteins, thus allowing triacylglycerol to accumulate. Theoretically, the lesion may be due to (1) a block in apolipoprotein synthesis, (2) a block in the synthesis of the lipoprotein from lipid and apolipoprotein, (3) a failure in provision of phospholipids that are found in lipoproteins, or (4) a failure in the secretory mechanism itself. 

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