Biosynthesis phospholipids

Two routes to phospholipid biosynthesis are known in either, the participation of CTP is necessary. The first route involves phosphatidic acid in phosphoglyceride biosynthesis. Phosphatidic acid reacts with CTP to yield CDP-diglyceride which, as a coenzyme, can participate in the transfer of diglyceride onto serine (or inositol) to produce phosphatidylserine (or phosphatidylinositol). Serine phosphatides are liable to decarboxylation (pyridoxal phosphate acting 

The second synthetic route involves activation of an alcohol (for example, choline) to produce CDP-choline. The latter participates in the transfer of choline onto diglyceride to form phosphatidylcholine. 

The phospholipids thus obtained are transported by lipid-carrier cytoplasmic proteins to the membranes (cellular or intracellular) to replace the used or impaired phospholipid molecules. 

The next step in phospholipid biosynthesis is catalyzed by 1-acylglycerol phosphate acyltransferase (the plsC gene product) which acylates the product of the PlsB step to form phosphatidic acid (Fig. 5). Phosphatidic acid comprises only about 0.1% of the total phospholipid in E. coli and turns over rapidly, a property consistent with its role as an intermediate in phospholipid synthesis. The 1-acylglycerol phosphate acyltransferase is thought to transfer unsaturated fatty acids selectively to the 2-position. The plsC gene is universally expressed in bacteria. 

coli possesses only three major phospholipid species in its membranes, making it one of the simplest organisms to study with regard to phospholipid biosynthesis. Phosphatidylethanolamine (PE) comprises the bulk of the phospholipids (75%), with PtdGro and Ptd2Gro forming the remainder (15-20% and 5-10%, respectively). The scheme for the synthesis of membrane phospholipids follows the classic Kennedy pathway (Fig. 6). 

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Phospholipid Biosynthesis Inhibitors. The organophosphate compounds ediphenphos [17109-49-8] (83) and iprobenphos [26087-47-8]... 

Pinkart HC, DC White (1997) Phospholipid biosynthesis and solvent tolerance in Pseudomonas putida strains. J Bacteriol 179 4219 226. 

Kent, C., 1995, Eukaryotic phospholipid biosynthesis, Anrar. Rev. Biochem. 64 315-343. 

Phospholipid turnover also takes place in an asymmetric manner. The enzymes responsible for phospholipid turnover in response to receptor-mediated phospholipase c activation are active from the cytoplasmic surface of the membrane. Likewise, diacylglycerol kinases converting the product of phospholipase c back into the key intermediate of phospholipid biosynthesis, phosphatidic acid, are also located on the cytoplasmic smface of the membrane (Sanjuan et al., 2001). 

Effect of Ceramides on Phospholipid Biosynthesis and Its Implication for Apoptosis... 

Cross-talk between ceramide and phospholipid biosynthesis... 

The structural similarity between arsenobetaine and glycine betaine suggested that arsenic may substitute for nitrogen in pathways of phospholipid biosynthesis and was the basis for a proposed biogenetic pathway for arsenobetaine (174). The proposed pathway begins with arsenic present as either arsenoethanolamine or arsenocholine. However, the origin of these two compounds is not discussed, and there has been no experimental evidence to support the hypothesis. 

Lecithins and related phospholipids usually contain a saturated fatty acid in the C-l position but an unsaturated acid, which may contain from one to four double bonds, at C-2. Arachidonic acid is often present here. Hydrolysis of the ester linkage at C-2 yields a l-acyl-3-phosphoglycerol, better known as a Iysophosphatidylcholine. The name comes from the powerful detergent action of these substances which leads to lysis of cells. Some snake venoms contain phospholipases that form Iysophosphatidylcholine. Lysophosphatidic acid (l-acyl-glycerol-3-phosphate) is both an intermediate in phospholipid biosynthesis (Chapter 21) and also a signaling molecule released into the bloodstream by activated platelets.15... 

The Final Reactions for Phospholipid Biosynthesis Occur on the Cytosolic Surface of the Endoplasmic Reticulum... 

This interconnected network of membrane vesicles is divided into two distinct parts. The rough endoplasmic reticulum (RER), which is studded with ribosomes, is the site of membrane and secretory protein biosynthesis and their post-translational modification. The smooth endoplasmic reticulum (SER) is involved in phospholipid biosynthesis and in the detoxification of toxic compounds. 

Sundler, R. and Akesson, B. (1975) Regulation of phospholipid biosynthesis in isolated rat hepatocytes, J. Biol. Chem. 250, 3359-3367. 

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