title: Mastoparan selectively activates phospholipase D2 in cell membranes.
abstract: Both known isoforms of phospholipase (PL) D, PLD1 and PLD2, require phosphatidylinositol 4,5-bisphosphate for activity. However, PLD2 is fully active in the presence of this phospholipid, whereas PLD1 activation is dependent on additional factors such as ADP-ribosylation factor-1 (ARF-1) and protein kinase Calpha. We find that mastoparan, an activator of G(i) and mast cells, stimulates an intrinsic PLD activity, most likely PLD2, in fractions enriched in plasma membranes from rat basophilic leukemia 2H3 mast cells. Overexpression of PLD2, but not of PLD1, results in a large increase in the mastoparan-inducible PLD activity in membrane fractions, particularly those enriched in plasma membranes. As in previous studies, expressed PLD2 is localized primarily in the plasma membrane and PLD1 in granule membranes. Studies with pertussis toxin and other agents indicate that mastoparan stimulates PLD2 independently of G(i), ARF-1, protein kinase C, and calcium. Kinetic studies indicate that mastoparan interacts synergistically with phosphatidylinositol 4,5-bisphosphate and that oleate, itself a weak stimulant of PLD2 at low concentrations, is a competitive inhibitor of mastoparan stimulation of PLD2. Therefore, mastoparan may be useful for investigating the regulation of PLD2, particularly in view of the well studied molecular interactions of mastoparan with certain other strategic signaling proteins.
authors.affiliation: Laboratory of Molecular Immunology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1760, USA.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Chahdi
authors.forename: Wahn Soo
authors.initials: WS
authors.lastname: Choi
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Kim
authors.forename: Michael A
authors.initials: MA
authors.lastname: Beaven
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D036341:Intercellular Signaling Peptides and Proteins; D015471:Leukemia, Basophilic, Acute; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology*; D019301:Oleic Acid / Q000494:pharmacology; D010455:Peptides; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism*; D051381:Rats; D014407:Tumor Cells, Cultured; D014862:Wasp Venoms / Q000494:pharmacology*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D019269:Phosphatidylinositol 4,5-Diphosphate; D014862:Wasp Venoms; D019301:Oleic Acid; C037500:mastoparan; C105606:phospholipase D2; D010739:Phospholipase D; C106801:phospholipase D1