Inositol phosphatides formation

Godfrey PP Potentiation by lithium of CMP-phosphatidate formation in carbachol-stimulated rat cerebral-cortical slices and its reversal by myo-inositol. Biochem J 258 621-624, 1989... 

Inositol phosphatides have another role in formation of microfilaments of the cytoske-leton. 

The mechanism of action and antitumor activity of 38a was studied [153]. Piericidin B1 N-oxide decreased EGF-stimulated phosphatidylinositol synthesis in a concentration dependent manner. It did not inhibit phosphatidic acid synthesis, phosphatidylinositol-4-kinasc, phospholipase C, protein kinase C, EGF receptor tyrosine kinase, EGF-induced inositol phosphate formation, DNA synthesis, RNA synthesis, or protein synthesis at concentrations which caused inhibition of phosphatidylinositol synthesis [153]. 

Fig. 6.11. Formation and function of diacylglycerol. The figure schematically shows two main pathways for formation of diacylglycerol (DAG). DAG can be formed from PtdInsP2 by the action of phospholipase C (PL-C). Another pathway starts from phosphatidyl chohne. Phospholipase D (PL-D) converts phosphatidyl choline to phosphatidic add (Ptd), and the action of phosphatases results in DAG. Arachidonic add, the starting point of biosynthesis of prostaglandins and other intracellular and extracellular messenger substances, can be cleaved from DAG. PKC protein kinase C Ptdins phosphatidyl inositol.

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. 

The mechanism of an increased phosphatidylinositol metabolism has been studied in platelets stimulated with thrombin in some detail. Thrombin stimulation leads to formation of the 1,2-diacylglyceride and inositol phosphate through hydrolysis by phospholipase C (Fig. 4). According to Majerus and coworkers, the diacylglyceride is then hydrolysed by a diglyceride lipase with liberation of arachidonic acid [35,40]. In contrast, Lapetina and his colleagues [41,42] propose that the diacylglyceride is phosphorylated to phosphatidic acid, a likely calcium ionophore [43], which in turn... 

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