Metabolism of structural lipids

Neuropathies can result from mutations that alter the structure or level of expression of PNS myelin proteins (e.g. overexpression of PMP22 in Charcot-Marie-Tooth syndrome (CMT) type 1A), the metabolism of myelin lipids (e.g. metachromatic leukodystrophy), or the capacity of PNS neurons to support their axons in patients with CMT caused by mutations of KIF1B [4] or NF-L [5, 6]. Both acquired and inherited amyloid neuropathies can result from the deposition of poorly soluble proteins, for example cryoglobulins or mutant transthyretins, in and around endoneurial bloodvessels [7-9]. 

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. 

Stroganov (1979) and Sidorov (1983) shed new light on viral and parasitic diseases in fish. In particular, it was found that many pathological infections affected the lipid metabolism. In some cases they led to a sharp fall in the reserve lipid content, and in others to excessively high values - the so-called fatty degeneration of the liver. The proportions and quantities of structural lipids are inevitably changed in one or another direction as soon as any pathology appears. 

The simplest topic covered in this chapter is that of choline, a compound with a 2-carbon backbone, which occurs in the diet and in the body mainly in the form of the structural lipid phosphatidylcholine. Choline is an issue in the metabolism of other lipids, namely, of phosphatidylserine, phosphatidylethanola-mine, and sphingomyelin. Phosphatidylino-sitol is a lipid that has received enormous attention from cell biologists because of its role in transmitting signals within the cell. Sphingomyelin is a structmal lipid in the plasma membrane, but it has received increased attention because of its role in regulating the growth, differentiation, and death of cells. 

Though numerous investigations show that TCA affects several biochemical processes of the plants—metabolism of sugars, lipids, nitrogen and enzyme reactions—this does not occur to an extent sufficient to explain the mode of action of a molecular level. As the protein-precipitating action of halogenated-alkanoic acids, hence of trichloroacetic acid, is well known, it is possible that the main biochemical action of TCA is the structural modification of proteins (Ashton and Crafts, 1973). 

This review attempts to emphasize recent developments in the study of glycerollpid metabolism in the chloroplast. Detailed current Information may be found in the recently published proceedings of a symposium on Structure, Function and Metabolism of Plant Lipids Q). 

Structure, Function and Metabolism of Plant Lipids" Siegenthaler, P.-A. Eichenberger, W. Eds. Elsevier Science Publishers B.V. Amsterdam, 1984. 

Sancholle, M. Weete, J. D. Touze-Soulet, J. M. Dargent, R. In "Structure, Function, and Metabolism of Plant Lipids" ... 

Various fatty acids are used in the production of structured lipids these may include both n-3 and n-6 fatty acids. Structured lipids containing MCFA and LCFA may modify the absorption rates because MCFA are rapidly oxidized for energy, whereas LCFA are oxidized very slowly. These specialty lipids are strucmrally and metabolically different from simple physical mixtures of medium-chain and long-chain triacylglycerols. 

Tuquet, C., Guillot-Salomon, T. and Farineau, N. (1984) In Structure, Function and Metabolism of Plant Lipids (P.A. Siegenthaler, W. Eichenberger, eds.) pp. 471-474, Elsevier... 

Nes W D, Heupel R C, Le P H 1974 A comparison of sterol biosynthesis in fungi and tracheophytes and its phylogenetic and functional implications. In Siegenthaler P A, Eichenberger W (eds) Structure, function, and metabolism of plant lipids. Elsevier Amsterdam, 207-216... 

Moore T.S., 1984 - Biochemistry and biosynthesis of plant acyl lipids in Structure, Function and Metabolism of Plant Lipids, Siegenthaler P.A.etEichenbergerW.,eds,Elsevier,Amsterdam, p. 93-96. 

Moreau P., Lessire R. and Casagne C. (1984) - In vivo membrane transfer of very long chain fatty acids synthesized by etiolated leek seedlings in Structure Function and Metabolism of plant Lipids, Siegenthaler P.A. et Eichenberger W., eds, Elsevier, Amsterdam, p. 307-310. 

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