The Role of Phospholipase D in Regulated Exocytosis |
| |
Authors: | Tatiana P Rogasevskaia Jens R Coorssen |
| |
Institution: | From the ‡Department of Biology, Mount Royal University, Calgary T3E 6K6, Canada and ;§Department of Molecular Physiology, School of Medicine and the Molecular Medicine Research Group, Western Sydney University, Penrith NSW 2751, Australia |
| |
Abstract: | There are a diversity of interpretations concerning the possible roles of phospholipase D and its biologically active product phosphatidic acid in the late, Ca2+-triggered steps of regulated exocytosis. To quantitatively address functional and molecular aspects of the involvement of phospholipase D-derived phosphatidic acid in regulated exocytosis, we used an array of phospholipase D inhibitors for ex vivo and in vitro treatments of sea urchin eggs and isolated cortices and cortical vesicles, respectively, to study late steps of exocytosis, including docking/priming and fusion. The experiments with fluorescent phosphatidylcholine reveal a low level of phospholipase D activity associated with cortical vesicles but a significantly higher activity on the plasma membrane. The effects of phospholipase D activity and its product phosphatidic acid on the Ca2+ sensitivity and rate of fusion correlate with modulatory upstream roles in docking and priming rather than to direct effects on fusion per se. |
| |
Keywords: | calcium docking membrane fusion phosphatidic acid Phospholipase D priming |
|
|