ARF1‐regulated phospholipase D in human neutrophils is enhanced by PMA and MgATP

Abstract
Human neutrophil PLD activity stimulated with GTP‐γ‐S was reconstituted with recombinant ARF1 in cytosol‐depleted cells. PMA‐pretreatment of intact cells greatly enhanced the subsequent reconstitution of the ARF1‐regulated PLD activity. This enhancement was only observed provided that the intact cells were pretreated with PMA, suggesting the stable recruitment of a cytosolic component, presumably protein kinase C, to the membranes. rARF1‐reconstituted PLD activity was not dependent on MGATP, but could be considerably enhanced by MgATP. Maximal effects of MgATP were seen at 1 mM. This enhancement by MgATP could not be attributed to protein kinase C. Neomycin was found to inhibit ARF1‐regulated PLD activity suggesting the requirement for polyphosphoinositides. We conclude: (i) that many of the observed effects of PMA may be dependent on the presence of the small GTP‐binding protein, ARF, and (ii) polyphosphoinositides are required for ARF1‐stimulated PLD activity.

This publication has 34 references indexed in Scilit: