Polyunsaturated membrane roles

Several strategies have been developed to characterise the structural and functional role of particular molecular species of membrane lipid. The use of phospholipid exchange or transfer proteins have been described to exchange one molecular species of a lipid class for another or enrich membranes in specific molecular species, respectivly. Another method has been to hydrogenate the double bonds of polyunsaturated membrane lipids in situ using homogeneous catalysts and to study the consequences of lipid saturation on membrane functions [2]. With the isolation of mutant strains of Arabidopsis defective in desaturation of chloroplast fatty acids [3,4] the question can be addressed directly without the problems associated with the use of exchange or transfer proteins or introduction of transition metal catalysts. 

Role of Nitric Oxide and Membrane Phospholipid Polyunsaturation in Oxidative Cell Death... 

They act as local messengers in tissues and they provide communication between one cell type and another within a single tissue or an organ (i.e. they have a paracrine effect). They are synthesised from the polyunsaturated fatty acids that contain 20 carbons (e.g. arachidonate, eicosapentaenoic acids). These fatty acids are generated from the hydrolysis of membrane phospholipids by the activity of a phospholipase which releases the fatty acids from position 2 of the phospholipids. Their roles are described in detail below. 

Yehuda S, Rabinovitz S, Carasso RL, Mostofsky DI. 2002. The role of polyunsaturated fatty acids in restoring the aging neuronal membrane. Neurohiol Aging 23 843-853. 

There were marked differences in the fatty acid patterns of the lipids of gills and kidneys, those from seawater fish possessing more w-3 in proportion to w-6 fatty acids and a higher proportion of total polyunsaturated fatty acids. They suggested that the role of polyunsaturates in membrane permeability and plasticity might account for the observation, and pointed out that the w-3 structure allows a greater degree of unsaturation than do the <0-6 or w-9 series. 

Litman, B., and D. Mitchell (1996). A role for phospholipid polyunsaturation in modulating membrane protein function. Lipids S193-S197. 

ROLE OF MEMBRANE POLYUNSATURATION IN OXIDATIVE CELL DEATH... 

Damage to polyunsaturated fatty acids tends to reduce membrane fluidity, which is known to be essential for the proper functioning of membranes [19]. However the precise role of such damage in contributing to reduced cell proliferation and/or cell death is still the subject of current investigation. Most of the proteins that play key roles in proliferative signal transduction actually function in a membrane environment, or in close association with membranes, and it is well established that the activity of integral membrane proteins is modulated by the lipids of the bilayer [51]. Moreover protein kinase C importantly has... 

Pyridoxal phosphate has a clear role in lipid metabolism as the coenzyme for the decarboxylation of phosphatidylserine, leading to the formation of phosphatidylethanolamine, and then phosphatidylcholine (Section 14.2.1), and membrane lipids from vitamin Bg-deficient animals are low in phosphatidylcholine (She et al., 1995). It also has a role, less well defined, in the metabolism of polyunsaturated fatty acids vitamin Bg deficiency results in reduced activity of A desaturase and impairs the synthesis of eicosapentanoic and docosahexanoic acids (Tsuge et al., 2000). 

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