Phosphatidylethanolamine regulation

The regulation of triacylglycerol, phosphatidylcholine, and phosphatidylethanolamine biosynthesis is driven by the availability of free fatty acids. Those that escape oxidation are preferentiaUy converted to phos-phohpids, and when this requirement is satisfied they are used for triacylglycerol synthesis. 

Therefore, it is currently believed that anandamide is formed from membrane phospholipids (Fig. 4) through a pathway that involves (1) a trans-acylation of the amino group of phosphatidylethanolamine with arachidonate from the sn-1 position of phosphatidylcholine and (2) a D-type phosphodiesterase activity on the resulting A-arachidonylphosphati-dylethanolamide (NAPE). Synthesis of anandamide is presumably regulated at the levels of both enzymes, the A-acyltranferase and the phospholipase D, by stimuli that raise intracellular calcium or by receptors linked with cAMP and PKA. It has been shown that anandamide is formed when neurons are depolarized and, therefore, the intracellular calcium ion levels are elevated (Cadas, 1996). 

Emoto, K., and Umeda, M., 2000, An essential role for a membrane phosphohpid in cytokinesis Regulation ofcontracthe ring disassembly by redistribution of phosphatidylethanolamine. J. Cell Biol., 149 1215-1224. 

Additional regulation of phosphatidylcholine and phosphatidylethanolamine biosynthesis occurs at the second step in the biosynthetic sequence (see fig. 19.4) where either CDP-choline or CDP-ethanolamine are made. For phosphatidylcholine biosynthesis, the activity of CTP phos-phocholine cytidylyltransferase (which makes CDP-choline) is governed by an unusual mechanism. The enzyme... 

Terova, B., Petersen, G., Hansen, H. S., and Slotte, J. P. (2005). V-Acyl phosphatidylethanolamines affect the lateral distribution of cholesterol in membranes. Biochim. Biophys. Acta 1715, 49 56. Terrazzino, S., Berto, F., Carbonare, M. D., Fabris, M., Guiotto, A., Bernardini, D., and Leon, A. (2004). Stearoylethanolamide exerts anorexic effects in mice via down-regulation ofliver stearoyl-coenzyme A desaturase-1 mma expression. FASEBJ. 18, 1580-1582. 

Kodaki, T., Hosaka, K., Nikawa, J.-I., and Yamashita, S., 1991a, Identification of the upstream activation sequences responsible for the expression and regulation of the PEM1 and PEM2 genes encoding the enzymes of the phosphatidylethanolamine methylation pathway in Saccharomyces cerevisiae. J. Biochem. 109 276-287. 

A number of the products of the decarboxylation of amino acids shown in Table 9.2 are important as neurotransmitters and hormones, such as dopamine, noradrenaline, adrenaline, serotonin (5-hydroxytryptamine), histamine, and Y - aminobutyric acid (GABA), and as the diamines agmatine andput-rescine and the polyamines spermidine and spermine, which are involved in the regulation of DNA metabolism. The decarboxylation of phosphatidylser-ine to phosphatidylethanolamine is important in phospholipid metabolism (Section 14.2.1). 

Holland JW, Hui C, Cullis PR, Madden TD (1996) Poly(ethylene glycol)-lipid conjugates regulate the calcium-induced fusion of liposomes composed of phosphatidylethanolamine... 

Kean, L.S., Grant, A.M., Angeletti, C., Mahe, Y., Kuchler, K., Fuller, R.S., and Nichols, J.W. (1997) Plasma membrane translocation of fluorescent-labeled phosphatidylethanolamine is controlled by transcription regulators, PDRl and PDR3. The Journal of Cell Biology, 138, 255-270. 

Fig. 4. In-sample temperature change with elapsed time after the commencement of heating hydrated phosphatidylethanolamine (a, b) and water (c) samples contained in 1 mm diameter capillaries using a temperature-regulated coaxial air stream. The thermal lag in (a) and (b) is due to the diversion of heat away from raising sample temperature and into chain melting which accounts for most of the enthalpy of the transition at 66 °C. T-jumps were from 30 °C to 92 °C (a, c) and 125 °C (b). The inset shows the calculated temperature profile across the capillary diameter in (a) as a function of time in seconds following the T-jump. Adapted from Ref. [31]...

Fig. 3. Regulation of PC biosynthesis via the CDP-choline pathway by modulation of the binding of CTP phosphocholine cytidylyltransferase (CT) to membranes. Three different modes of regulation of CT activity are indicated. The abbreviations are CK, choline kinase CPT, CDP-choline 1,2-diacylglycerol cholinephos-photransferase PEMT, phosphatidylethanolamine Af-methyltransferase PC, phosphatidylcholine PE, phos-phatidylethanolamine DG, diacylglycerol.

C. butyricum appears to regulate the stability of the bilayer arrangement of membranes by altering the ratio of ether versus acyl ethanolamine phospholipids in response to changes in the degree of lipid unsaturation of the membranes. Experiments with bacteria indicate that substitution of plasmenylethanolamine for phosphatidylethanolamine in biomembranes would have only small effects on lipid melting transitions, whereas the tendency to form non-lamellar lipid structures would be significantly increased. 

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