Ethanolamine, choline

Ethanolamine Choline HOCH2CH2NHj HOCH2CH2N+(CH3)3 Phosphatidylethanolamine Phosphatidylcholine also called Lecithin PE PC... 

Fig. 2. General scheme for transduction of ACTH signal from plasma membrane to mitochondria in the adrenal cortex. CHX, cycloheximide TG. triglyceride CE, cholesterol ester Lts, leukotrienes PGs, prostaglandins SCP2, sterol carrier protein PE, PC, PI, phosphatidyl ethanolamine, choline and inositol (from Ref. 25, with permission).

The major phosphoglycerides are derived from phosphatidate by the formation of an ester bond between the phosphate group of phosphatidate and the hydroxyl group of one of several alcohols. The common alcohol moieties of phosphoglycerides are the amino acid serine, ethanolamine, choline, glycerol, and the inositol. 

Figure 2.4 The structures of cholesterol and phospholipids. R1 and R2 = palmityl, stearyl or oleyl. R3 = ethanolamine, choline, serine, inositol or glycerol.

O Brien JS, Eillerup DL, Mead JF. Quantification and fatty acid and fatty aldehyde composition of ethanolamine, choline, and serine glycerophosphatides in human cerebral gray and white matter. J Lipid Res 1964 5 329-338. 

Phosphatidic acids are the simplest phosphoacylglycerols and are present only in small amounts in membranes. The most common phosphoacylglycerols in membranes have a second phosphate ester linkage. The alcohols most commonly used to form this second ester group are ethanolamine, choline, and serine. Phosphatidylethanolamines are also called cephalins, and phosphatidylcholines are called lecithins. Used as emulsifying agents, lecithins are added to foods such as mayonnaise to prevent the aqueous and fat components from separating. 

R R =alkyl groups, B = ethanolamine, choline, serine or inositol... 

The parent molecule of the phospholipid family is phosphatidic acid (Fig. 36.1). It consists of a glycerol backbone to which are esterified two fatty acyl molecules (palmitic acid is shown here) and phosphoric acid. The latter produces a phosphate which is free to react with the hydroxyl groups of serine, ethanolamine, choline or inositol to form phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine or phosphatidylinositol, respectively. 

The composition of natnral membranes is complex with phospholipids as the main component (see Supramolecular Chemistry of Membranes, Snpramolecnlar Aspects of Chemical Biology). Phospholipids are typically formed by a glycerol moiety esterified with two fatty acid gronps and a phosphoric acid group, which in tnm is esterified by another group such as ethanolamine, choline, or serine (Fignre 1). 

Further esterification of the phosphoric acid part with a low-molecular-weight alcohol, most commonly ethanolamine, choline, serine, or inositol, gives a phospholipid. 

CDP-choline (CDP-ethanolamine) choline (ethanolamine) phosphottansferase, are localized in the endoplasmic reticulum. The acylation of dihydroxyacetone phosphate (DHAP) by acyl-coenzyme A (acyl-CoA) is catalysed by dihydroxyacetone phosphate acyltransferase with formation of... 

Fig. 1. Hypothetical cycle of metabolism involving glycine, serine, ethanolamine, choline, and betaine.

Glycine is utilized in numerous synthetic processes such as the formation of purines, porphyrins, creatine, ethanolamine, choline, and glutathione. These reactions are discussed in other chapters of this work. This section is devoted to a narration of the pathways of catabolism of glycine. 

Plasmalogens ( acetal phosphatides ) Glycerol ester and enol ether Ethanolamine, choline 1 1... 

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