Different sensitivity to phorbol esters and pertussis toxin of bombesin- and platelet-derived growth factor-induced, phospholipase C-mediated hydrolysis of phosphoinositides in NIH/3T3 cells.
Incubation of the serum-deprived cultures of NIH/3T3 cells with bombesin or platelet-derived growth factor (PDGF) induced the phospholipase C-mediated hydrolysis of phosphoinositides. Protein kinase C-activating 12-O-tetradecanoylphorbol 13-acetate (TPA) and pertussis toxin inhibited the bombesin-induced phospholipase C reactions. AlF4-, a direct activator of GTP-binding proteins (G proteins), also induced the phospholipase C reactions and TPA inhibited the AlF4- -induced reactions. These results suggest that a pertussis toxin-sensitive G protein is involved in the coupling of the bombesin receptor to the phospholipase C and that the coupling of the G protein to the phospholipase C is inhibited by protein kinase C. In contrast, neither TPA nor pertussis toxin inhibited the PDGF-induced phospholipase C reactions, indicating that a pertussis toxin-sensitive G protein is not involved in the coupling of the PDGF receptor to the phospholipase C and that this coupling is insensitive to protein kinase C. These results suggest that the regulatory mechanism of the PDGF receptor for the phospholipase C activation is different from that of the bombesin receptor.
Hoshijima
M
M
Department of Biochemistry, Kobe University School of Medicine, Japan.
Ueda
T
T
Hamamori
Y
Y
Ohmori
T
T
Takai
Y
Y
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D002478:Cells, Cultured; D006868:Hydrolysis; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D008565:Membrane Proteins; D010716:Phosphatidylinositols; D010982:Platelet-Derived Growth Factor; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D013755:Tetradecanoylphorbol Acetate; D001839:Bombesin