Jq. Luo et al., RALA INTERACTS DIRECTLY WITH THE ARF-RESPONSIVE, PIP2-DEPENDENT PHOSPHOLIPASE D1, Biochemical and biophysical research communications, 235(3), 1997, pp. 854-859
RalA GTPase associates with a phospholipase D (PLD) that is activated
in v-Src- and v-Ras-transformed cells. TWO mammalian PLDs were recentl
y 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, an
d 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 ar
gue that RalA associates directly with the Arf-responsive, PIP2-depend
ent PLD1. (C) 1997 Academic Press.