Glycerophospholipids phosphatidylserine

Our first issue with respect to the lipid bilayer is its composition. This varies from membrane to membrane but generally includes several glycerophospholipids— phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine—as well as... 

The phospholipids in milk are synthesized by the mammary cell via pathways that are common to other mammalian cells. For further information on the synthesis of phospholipids in the mammary cell, see Kinsella and Infante (1978) and Patton and Jensen (1976). The major glycerophospholipids are phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, and phosphatidylinositol. A more complete composition is given in Table 4.6, Patton and Jensen (1976). The acyl and alkyl compositions will be given later. In milk, the glycerophospholipids are found predominantly in the diacyl form. However, small... 

Glycerophospholipids contain a glycerol skeleton to which two fatty acids are esterified saturated fatty acids occupy mostly sn-position 1, whereas unsaturated fatty acids are mainly present on sn-position 2. The third hydroxyl is linked to a phosphate group to which an organic base is mostly esterified (Fig. 1). The most important components of soybean lecithin are phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI). Phosphatidic acid (PA) may become important due to the presence of phospholipase D this enzyme slowly converts PC into PA in vegetable lecithins. Phosphatidylserine (PS), phosphatidylglycerol (PG), and lyso-phosphatidylcholine (LPC) are known as minor components lysophospholipids contain only one acyl group per molecule. Besides, ether phospholipids occur in which one or both fatty acyl... 

The structure of glycerophospholipids is characterized by a l,2-diacyl-3-phospho-5n-glycerol, or phosphatidyl moiety, and a variable headgroup linked to the phosphate. Major phosphoglycerides found in nature are phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine, phosphatidylinositol (PI), and diphospha-... 

Glycerophospholipids which can be analysed in this way [285] include the cephalins (R = ethanolamine), phosphatidylserine [287], phos-phatidylinositol, and phosphatidylcholine. 

Phosphatidylinositol is uncommon in bacteria and is found in a few Gram-positive species only. In actinomycetes and a few other bacteria mannosides of phosphatidylinositol may be present. Other glycerophospholipids such as phosphatidic acid and phosphatidylserine have a widespread occurrence in bacteria but only in small amounts. Both of these lipids play an important role as metabolic intermediates (Finnerty, 1978 Raetz, 1978). 

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