Augmentation by calmodulin of ADP-ribosylation factor-stimulated phospholipase D activity in permeabilized rabbit peritoneal neutrophils

K. I. Takahashi, K. Tago, H. Okano, Y. Ohya, T. Katada, Y. Kanaho

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Activation of the membrane-bound phospholipase D (PLD) requires cytosolic factor(s), and ADP-ribosylation factor (ARF) has been identified as a cytosolic PLD activator. In the present study, we demonstrate that calmodulin (CaM) and ARF are both involved in PLD activation in rabbit peritoneal neutrophils. The PLD activity of streptolysin O-permeabilized, cytosol- depleted rabbit neutrophils was significantly enhanced when the permeabilized cells were reconstituted with bovine brain cytosol in the presence of guanosine 5'-O-(3-thiotriphosphate) (GTPγS), whereas there was little activation of the enzyme in the absence of cytosol. The GTPγS-stimulated PLD activity in the presence of cytosol was augmented on increasing the concentration of free Ca2+. The PLD activity stimulated by GTPγS and Ca2+ in this system was inhibited by the calmodulin inhibitor W-7. These findings suggest that CaM plays a role as a cytosolic PLD activator. Moreover, highly purified CaM alone, as well as partially purified ARF alone, promoted a slight stimulation of the PLD activity in permeabilized neutrophils. Interestingly, ARF-stimulated PLD activity was augmented by CaM in the presence of GTPγS and Ca2+. This augmentation was again inhibited by W-7, as well as by the structurally unrelated CaM inhibitor trifluoperazine. These data imply that CaM stimulates the PLD activity of rabbit neutrophils in concert with ARF.

Original languageEnglish
Pages (from-to)1229-1234
Number of pages6
JournalJournal of Immunology
Issue number3
Publication statusPublished - 1996 Feb 6
Externally publishedYes


ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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