CDP-diacylglycerols

Eukaryotes Synthesize Glycerolipids from CDP-Diacylglycerol or Diacylglycerol... 

FIGURE 25.19 Diacylglycerol and CDP-diacylglycerol are the principal precursors of glycerolipids in eukaryotes. Phosphatidylethanolamine and phosphatidylcholine are formed by reaction of diacylglycerol with CDP-ethanolamine or CDP-choline, respectively. 

FIGURE 25.22 CDP-diacylglycerol is a precursor of phosphaddylinositol, phosphaddyl-glycerol, and cardiolipin in eukaryotes. 

Heacock, A.M., Uhler, M. D. and Agranoff, B. W. Cloning of CDP-diacylglycerol synthase from a human neuronal line. /. Neurochem. 67 2200-2203,1996. 

The CDP diacylglycerol reacts directly with inositol as follows. 

Transfer of a CMP residue gives rise first to CDP-diacylglycerol (enzyme phosphatida-tecytidyl transferase 2.3.1.22). 

This enzyme [EC 2.7.7.41], also known as CTP phospha-tidate cytidylyltransferase and CDP-diacylglycerol synthase, catalyzes the reaction of CTP with phosphatidate to produce CDP-diacylglycerol and pyrophosphate. 

This transferase, officially known as CDP-diacylglycerol—serine O-phosphatidyltransferase [EC 2.7.8.8],... 

PHOSPHATIDYLINOSITOL SYNTHASE CDP-Diacylglycerol L-serine O-phosphatidyl-transferase,... 

Watson SP, Shipman L, Godfrey PP Lithium potentiates agonist formation of [3h]CDP-diacylglycerol in human platelets. Eur J Pharmacol 188 273-276, 1990... 

Eukaryotes Synthesize Anionic Phospholipids from CDP-Diacylglycerol... 

In eukaryotes, phosphatidylglycerol, cardiolipin, and the phosphatidylinositols (all anionic phospholipids see Fig. 10-8) are synthesized by the same strategy used for phospholipid synthesis in bacteria. Phosphatidylglycerol is made exactly as in bacteria. Cardiolipin synthesis in eukaryotes differs slightly phosphatidylglycerol condenses with CDP-diacylglycerol (Fig. 21-26), not another molecule of phosphatidylglycerol as in E. coli (Fig. 21-25). 

Phosphatidylinositol is synthesized by condensation of CDP-diacylglycerol with inositol (Fig. 21-26). Specific phosphatidylinositol kinases then convert phosphatidylinositol to its phosphorylated derivatives (see Fig. 10-17). Phosphatidylinositol and its phosphorylated products in the plasma membrane play a central role in signal transduction in eukaryotes (see Figs 12-8, 12-19). 

Yeast, like bacteria, can produce phosphatidylserine by condensation of CDP-diacylglycerol and serine, and can synthesize phosphatidylethanolamine from phosphatidylserine in the reaction catalyzed by phosphatidylserine decarboxylase (Fig. 21-27). In mammalian ceils, an alternative route to phosphatidylserine is a head-group... 

In mammals, phosphatidylserine is not synthesized from CDP-diacylglycerol instead, it is derived from phosphatidylethanolamine via the head-group exchange reaction (Fig. 21-27). Synthesis of phosphatidylethanolamine and phosphatidylcholine in mammals occurs by strategy 2 of Figure 21-24 phosphorylation and activation of the head group, followed by condensation with... 

In bacteria, phosphatidylserine is formed by the condensation of serine with CDP-diacylglycerol decarboxylation of phosphatidylserine produces phosphatidylethanolamine. Phosphatidylglycerol is formed by condensation of CDP-diacylglycerol with glycerol 3-phosphate, followed by removal of the phosphate in monoester linkage. 

PI is synthesized from free inositol and CDP-diacylglycerol as shown in Figure 17.5. PI is an unusual phospholipid in that it olten contains stearic acid on carbon 1 and arachidonic acid on carbon 2 of the glycerol. PI, therefore, serves as a reservoir of arachidonic j acid in membranes and, thus, provides the substrate fa-prostaglandin synthesis when required (see p. 211 for a discussion of these compounds). 

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