title: Evidence that v-Src-induced phospholipase D activity is mediated by a G protein.
abstract: v-Src-induced increases in diglyceride are derived from phosphatidylcholine via a type D phospholipase (PLD) and a phosphatidic acid phosphatase. v-Src-induced PLD activity, as measured by PLD-catalyzed transphosphatidylation of phosphatidylcholine to phosphatidylethanol, is inhibited by GDP beta S, which inhibits G-protein-mediated intracellular signals. Similarly, v-Src-induced increases in diglyceride are also blocked by GDP beta S. In contrast to the PLD activity induced by v-Src, PLD activity induced by the protein kinase C agonist, 12-O-tetradecanoylphorbol-13-acetate (TPA), was insensitive to GDP beta S. Consistent with the involvement of a G protein in the activation of PLD activity by v-Src, GTP gamma S, a nonhydrolyzable analog of GTP that potentiates G-protein-mediated signals, strongly enhanced PLD activity in v-Src-transformed cells relative to that in parental BALB/c 3T3 cells. The effect of GTP gamma S on PLD activity in v-Src-transformed cells was observed only when cells were prelabeled with [3H]myristate, which is incorporated exclusively into phosphatidylcholine, the substrate for the v-Src-induced PLD. There was no difference in the effect of GTP gamma S-induced PLD activity on v-Src-transformed and BALB/c 3T3 cells when the cells were prelabeled with [3H]arachidonate, which is not incorporated into phospholipids that are substrates for the v-Src-induced PLD. Similarly, GDP beta S inhibited PLD activity in v-Src-transformed cells much more strongly than in BALB/c 3T3 cells when [3H]myristate was used to prelabel the cells. The GTP-dependent activation of PLD by v-Src was dependent upon the presence of ATP but was unaffected by either cholera or pertussis toxin. These data suggest that v-Src induces PLD activity through a phosphorylation event and is mediated by a cholera and pertussis toxin-insensitive G protein.
authors.affiliation: Institute for Biomolecular Structure and Function, Hunter College, City University of New York, New York 10021.
authors.forename: H
authors.initials: H
authors.lastname: Jiang
authors.forename: K
authors.initials: K
authors.lastname: Alexandropoulos
authors.forename: J
authors.initials: J
authors.lastname: Song
authors.forename: D A
authors.initials: DA
authors.lastname: Foster
mesh_terms: D016475:3T3 Cells; D000227:Adenine Nucleotides / Q000494:pharmacology; D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001358:Avian Sarcoma Viruses / Q000235:genetics; D016227:Benzoquinones; D002461:Cell Line, Transformed; D002772:Cholera Toxin / Q000494:pharmacology; D004790:Enzyme Induction; D005459:Fluorides / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D047029:Lactams, Macrocyclic; D051379:Mice; D008807:Mice, Inbred BALB C; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D017607:Aluminum Compounds; D016227:Benzoquinones; D047029:Lactams, Macrocyclic; D009227:Myristic Acids; D010713:Phosphatidylcholines; D011809:Quinones; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D019814:Myristic Acid; D006153:Guanosine Diphosphate; D017828:Rifabutin; D016718:Arachidonic Acid; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C020754:herbimycin; C023427:guanosine 5'-O-(2-thiodiphosphate); D002772:Cholera Toxin; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src); D010739:Phospholipase D; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D005459:Fluorides; C032311:aluminum fluoride