title: G-protein dissociation, GTP-GDP exchange and GTPase activity in control and PMA treated neutrophils stimulated by fMet-Leu-Phe.
abstract: The addition of the chemotactic factor fMet-Leu-Phe to cell homogenates causes a decrease in the pertussis toxin catalyzed ADP-ribosylation of a 41 kDa protein. The fMet-Leu-Phe induced decrease is not abolished in homogenates prepared from phorbol 12-myristate 13-acetate treated neutrophils. This decreased ribosylation probably reflects a dissociation of the GTP-binding protein oligomer that is not followed by association, possibly because of the release of the alpha-subunit into the suspending medium. Furthermore, fMet-Leu-Phe stimulates the binding of radiolabelled guanylylimidodiphosphate to membrane preparations. Again, the stimulated binding of guanylylimidodiphosphate is not affected by treating the intact neutrophils with phorbol 12-myristate 13-acetate. In addition leukotriene B4, platelet activating factor and fMet-Leu-Phe activate a high-affinity GTPase in membrane preparations. The basal level of this GTPase activity is dramatically inhibited in membrane preparations isolated from cells treated with phorbol 12-myristate 13-acetate. On the other hand, the fMet-Leu-Phe stimulated component is only marginally reduced. The present findings suggest that PMA does not prevent receptor G-protein interaction.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000097:blood; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002474:Cell-Free System; D020558:GTP Phosphohydrolases / Q000097:blood*; D019204:GTP-Binding Proteins / Q000097:blood*; D006153:Guanosine Diphosphate / Q000097:blood; D006160:Guanosine Triphosphate / Q000097:blood; D007975:Leukotriene B4 / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000378:metabolism*; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases / Q000097:blood*; D010972:Platelet Activating Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000097:blood; D011817:Rabbits; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D010972:Platelet Activating Factor; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D007975:Leukotriene B4; D000246:Adenosine Diphosphate Ribose; D009240:N-Formylmethionine Leucyl-Phenylalanine; D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate