title: The Role of Phospholipase D in Regulated Exocytosis.
abstract: There are a diversity of interpretations concerning the possible roles of phospholipase D and its biologically active product phosphatidic acid in the late, Ca(2+)-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 Ca(2+) sensitivity and rate of fusion correlate with modulatory upstream roles in docking and priming rather than to direct effects on fusion per se.
authors.affiliation: From the Department of Biology, Mount Royal University, Calgary T3E 6K6, Canada and trogasevskaia@mtroyal.ca.
authors.forename: Tatiana P
authors.initials: TP
authors.lastname: Rogasevskaia
authors.affiliation: Department of Molecular Physiology, School of Medicine and the Molecular Medicine Research Group, Western Sydney University, Penrith NSW 2751, Australia j.coorssen@uws.edu.au.
authors.forename: Jens R
authors.initials: JR
authors.lastname: Coorssen
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D005089:Exocytosis / Q000502:physiology*; D008561:Membrane Fusion / Q000502:physiology*; D009865:Oocytes / Q000166:cytology / Q000201:enzymology*; D010712:Phosphatidic Acids / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism*; D047270:Strongylocentrotus purpuratus / Q000166:cytology / Q000201:enzymology*
chemical_list: D010712:Phosphatidic Acids; D010739:Phospholipase D; D002118:Calcium
keywords: Phospholipase D; calcium; docking; membrane fusion; phosphatidic acid; priming