Receptor-stimulated dissociation of GTP[S] from Gi-proteins in membranes of HL-60 cells.
Formyl peptides stimulate binding of the stable GTP analogue, guanosine 5'-O-[gamma-thio]triphosphate (GTP[S]), to G-proteins in membranes of myeloid differentiated human leukaemia (HL-60) cells. On the other hand, agonist-activated formyl peptide receptors can also cause rapid and substantial release of GTP[S] bound to HL-60 membrane G-proteins. For fMet-Leu-Phe-stimulated dissociation of labelled GTP[S], an additional guanine nucleotide, in the potency order, unlabelled GTP[S] >> GTP >> guanosine 5'-[beta,gamma-imino]triphosphate > or = guanosine 5'-O-[beta-thio]diphosphate > or = GDP > GMP = ATP (no effects at 1 mM), was absolutely necessary. While with unlabelled GTP[S] and GTP similar concentrations were required for control and fMet-Leu-Phe-stimulated release, about 50-100-fold higher concentrations of the other nucleotides were necessary for agonist-stimulated than for basal release of bound GTP[S]. The receptor action appeared to be catalytic, required Mg2+ and was pertussis toxin sensitive. The data indicate that binding of GTP[S] to HL-60 membrane G-proteins is reversible and that agonist-activated formyl peptide receptors can interact, either directly or indirectly, with GTP[S]-liganded Gi-proteins, resulting in release of bound GTP[S].
Institut für Pharmakologie, Universität GH Essen, F.R.G.
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D001665:Binding Sites; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D037342:Pertussis Toxin; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D006150:Guanine Nucleotides; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins