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Biochem Biophys Res Commun. 1996 Mar 27;220(3):484-90.

GTPgammaS-stimulated phospholipase D activation in human neutrophils occurs by protein kinase C-dependent and -independent pathways but not tyrosine kinases.

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Department of Haematology, University of Liverpool, United Kingdom.


Addition of GTPgammaS to saponin-permeabilised human neutrophils activated both the NADPH oxidase and phospholipase D (PLD). This PLD activation was hardly affected by staurosporine or Ro31-8220 (at concentrations which inhibited PMA stimulated PLD activity), indicating that it was largely independent of protein kinase C (PKC). This GTPgammaS stimulated PLD activity was enhanced by 1 mM ATP, but this ATP-enhanced activity was blocked by inhibitors of PKC. Addition of GTPgammaS resulted in very low levels of phosphorylation on tyrosine residues, but higher levels of phosphorylation on serine/threonine residues. Addition of pervanadate hydroperoxides stimulated phosphorylation on tyrosine residues and activated PLD which was blocked by addition of inhibitors of tyrosine kinases. Thus, GTPgammaS can stimulate PKC-dependent and -independent pathways of PLD activation. Whilst phosphorylation on tyrosine residues can result in activation of PLD, this is regulated independently of activation via G-proteins.

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