Membrane phospholipase

Toxins that Attack the Cell Membrane Phospholipases and Pore-Forming Toxins 150... 

The same basic biochemical control mechanism causes contraction of the smooth muscle as well as secretion of aldosterone. The binding of angiotensin to its receptor activates a membrane phospholipase-C. It catalyses the hydrolysis of phosphoinositide phosphatidylinositol bis-phosphate to produce the two intracellular messengers, inositol trisphosphate (IP3) and diacylglycerol (DAG). 

A second class of serpentine receptors are coupled through a G protein to a plasma membrane phospholipase C (PLC) that is specific for the plasma membrane lipid phosphatidylinositol 4,5-bisphosphate (see Fig. 10-15). This hormone-sensitive enzyme catalyzes the formation of two potent second messengers diacyl-glycerol and inositol 1,4,5-trisphosphate, or IP i (not to be confused with PIP3, p. 431). 

Stella N., Pellerin L., and Magistretti P. J. (1995). Modulation of the glutamate-evoked release of arachidonic acid from mouse cortical neurons Involvement of a pH-sensitive membrane phospholipase A2. J. Neurosci. 15 3307-3317. 

Snijder, H. J., Ubarretxena-Belandia, I., Blaauw, M., Kalk, K. H., Verhij, H. M., Egmond, M. R., Dekker, N., and Dijkstra, B. W. (1999). Structural evidence for dimerization-regulated activation of an integral membrane phospholipase. Nature401, 717-721. 

As shown in Figure 14.6, a proportion of the phosphatidylinositol in membranes undergoes two successive phosphorylations to yield phosphatidylinositol bisphosphate. This is a substrate for hormone-sensitive phospholipase C, which is activated by the G-protein-GTP complex released into the cell membrane by a hormone receptor following binding of the hormone at the outer surface of the membrane. Phospholipase C hydrolyzes phosphatidylinositol bisphosphate to release diacylglycerol and inositol trisphosphate. 

Snijder HJ, Timmins PA, Kalk KH, Dijkstra BW. Detergent organ- 64. isation in crystals of monomeric outer membrane phospholipase... 

Horrevoets, A. J. G., et al.. Inactivation of Escherchia coli Outer-Membrane Phospholipase A by the Affinity Label Hexadecanesulfonyl Fluoride, Eur. J. Biochem., 198 247-253 (1991). 

Two PLAs have been purified from Escherichia coli based on their differential sensitivity to treatment with detergents [2]. A detergent-insensitive enzyme is localized in the outer membrane, whereas a detergent-sensitive enzyme is found on the cytoplasmic membrane and in soluble fractions. The outer membrane enzyme, known as outer membrane phospholipase A, has broad substrate specificity and demonstrates PLA, PLAj, lysophospholipase A, and lysophospholipase Aj activity as well as activity for hydrolyzing monoacylglycerols and diacylglycerols. The crystal structure allows a more detailed discussion of an integral membrane phospholipase [12]. 

Fig. 4. Crystal structure of the outer membrane phospholipase A dimer from E. coli shown in the plane of the membrane. The top half of the molecule is located in the lipopolysaccharide monolayer facing the exterior of the cell. The phospholipid monolayer of the outer cell membrane would be located around the bottom half of the protein. Two calcium ions are shown at the active sites while Ser-144 of each active site is covalently modified with a hexadecylsulfonyl moiety represented in a ball and stick format. Structure is adapted from Ref. [12]. (See color plate section, plate no. 8.)...

Snijder, H.J., Dijkstra, B.W. 2000. Bacterial phospholipase A structure and function of an integral membrane phospholipase. Biochim. Biophys. Acta/Mol Cell Biol. Lipids 1488 91-101. 

Lapetina EG, Schmitges CJ, Chandrabose K and Cuatrecasas P. Cyclic AMP and prostacyclin inhibit platelet membrane phospholipase. Biochem. Biophys. Res. Commun. 76, 828-835, 1977. 

Serine/threonine kinase Cytoskeleton/cell membrane Phospholipase Serine kinase Protein kinase Transcription activation DNA damage repair DNA damage repair Ras-GTPase RNA polymerase Rapamycin associated protein Adapter... 

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