RalA interacts directly with the Arf-responsive, PIP2-dependent phospholipase D1.
RalA GTPase associates with a phospholipase D (PLD) that is activated in v-Src- and v-Ras-transformed cells. Two mammalian PLDs were recently cloned: PLD1, which is activated by Arf family GTPases and dependent upon phosphatidylinositol-4,5-bisphosphate (PIP2), and PLD2, which is also dependent upon PIP2, but not stimulated by Arf. Another PLD has been described that is stimulated by oleate. Evidence is provided that the RalA-assiciated PLD is PLD1. First, the PLD precipitated by RalA from murine fibroblasts was stimulated by Arf, dependent upon PIP2, and inhibited by oleate. Second, immobilized RalA precipitated PLD1 from sf9 insect cells overexpressing PLD1. Third, a series of RalA mutants precipitated PLD activity from both PLD1-expressing insect cells and murine fibroblasts with the same efficiency. And finally, immobilized RalA precipitated PLD1 from a purified PLD1 preparation. These data argue that RalA associates directly with the Arf-responsive, PIP2-dependent PLD1.
Luo
J Q
JQ
Department of Biological Sciences, Hunter College of The City University of New York, New York 10021, USA.
Liu
X
X
Hammond
S M
SM
Colley
W C
WC
Feig
L A
LA
Frohman
M A
MA
Morris
A J
AJ
Foster
D A
DA
D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D020558:GTP Phosphohydrolases / Q000302:isolation & purification / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016391:Genes, src; D005982:Glutathione Transferase; D051379:Mice; D019301:Oleic Acid / Q000494:pharmacology; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000494:pharmacology; D010739:Phospholipase D / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D018411:Spodoptera; D014162:Transfection
D019269:Phosphatidylinositol 4,5-Diphosphate; D011993:Recombinant Fusion Proteins; D019301:Oleic Acid; D005982:Glutathione Transferase; D010739:Phospholipase D; C106801:phospholipase D1; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins