Triacylglycerol lipid biosynthesis

FIGURE 21-18 Phosphatidic acid in lipid biosynthesis. Phosphatidic acid is the precursor of both triacylglycerols and glycerophospholipids. The mechanisms for head-group attachment in phospholipid synthesis are described later in this section. 

Although the mechanism of formation of unsaturation may well proceed as for the polyethenoid fatty acids, it is of interest that palmitoleic acid was not found to be incorporated (ref. 83). The conclusion was drawn that in the biosynthesis of anacardic acid, the side chain was in a different state of activation and/or site than in the case of the triacylglycerol lipids. Some of these of course are found in the oil in the cashew kernel. 

Since erucic acid (fZJ-13 22 1) is confined almost exclusively to the neutral lipid fraction in developing oilseeds [112], this fatty acid is an ideal marker for investigating enzymes involved in storage lipid biosynthesis. However, the mechanism for incorporation of (ZJ-13 22 1 into triacylglycerols is not fully understood, despite several studies aimed at elucidating the pathway in various oilseeds [113-119]. This is, in part, due to the fact that, traditionally, metabolism... 

Mukherjee, K. D. (1983) Lipid biosynthesis in developing mustard seed. Formation of triacylglycerols from endogenous and exogenous fatty acids. Plant Physiol. 

Polar lipids (PL) were the important radioactive component in lipid seeds on 3 WAA it represent 82% of total labelled fatty acids after one hour acetate incubation. In these case triacylglycerols (TAG) biosynthesis was slow and reached 13 % [fig. 3]. 

In plants, triacylglycerols are mainly synthesized and stored in the cotyledons of the seed (e.g. sunflower, soya, rape), the mesocarp of the fruit (avocado, oil palm) or the endosperm tissue (castor bean, coconut). Although the main pathways for the biosynthesis of triacylglycerols in plants have now been elucidated, the control of lipid biosynthesis in plants is little understood. 

Section 26 4 Phospholipids are intermediates in the biosynthesis of triacylglycerols from fatty acids and are the principal constituents of the lipid bilayer component of cell membranes... 

Phosphatidic acids not only are intennediates in the biosynthesis of triacylglycerols but also are biosynthetic precursors of other members of a group of compounds called phosphoglycerides or glycerol phosphatides. Phosphorus-containing derivatives of lipids are known as phospholipids, and phosphoglycerides are one type of phospholipid. 

Familial adenomatous polyposis 574 Faraday, numerical value of 283 Farnesyl group 402, 559 Fat(s). See also Triacylglycerol (triglyceride) composition of 380 hydrolysis of 507 Fatty acid(s) 380-382 activation of 512 acyl CoA, derivatives of 507 biosynthesis of 722 branched chain 381 cyclopropane-containing 399 essential 721 in lipids 380 names of, table 380 oxidation 511 pKa values of 380 stability of 589... 

Outline of pathways for the biosynthesis of major cellular lipids (other than cholesterol) in a mammalian cell. Most of the metabolism of these lipids occurs on membrane surfaces because of the insoluble nature of the substrates and products. These lipids play three major roles (l) they act as a storehouse of chemical energy, as with triacylglycerols (2) they are structural components of membranes (boxed compounds) and (3) they act as regulatory compounds (underlined), either as eicosanoids, which act as local hormones, or as phosphorylated inositols and diacylglycerols, which function as second messengers. 

The synthesis of the apoproteins takes place on ribosomes that are bound to the endoplasmic reticulum. As we mentioned previously, the biosynthesis of the other lipids in lipoproteins (cholesterol, triacylglycerols, and phospholipids) also occurs on the endoplasmic reticulum. 

Lin, J. T., Woodruff, C. L., Lagouche, O. J., McKeon, T. A., Stafford, A. E., Goodrich-Tanrikulu, M., Singleton, J. A., and Haney C. A. 1998. Biosynthesis of triacylglycerols containing ricinoleate in castor microsomes using l-acyl-2-oleoyl- wj-glycerol-3-phosphocholine as the substrate of oleoyl-12-hydroxylase. Lipids, 33, 59-69. 

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