Association of guinea pig lung bombesin receptors with pertussis toxin-sensitive guanine nucleotide binding proteins.
The possible interaction of bombesin receptors with guanine nucleotide binding protein in guinea pig lung was studied. The non-hydrolysable GTP analogue guanosine-5'-[gamma-thio]triphosphate (GTP gamma S) was shown to decrease [125I-Tyr4]bombesin binding in a concentration-dependent manner. The specificity of this effect was assessed by examining the effects of other guanine nucleotides on this binding at a concentration of 1 mM. GMP and GDP weakly inhibited [125I-Tyr4]bombesin binding (2 and 19%, respectively), whereas GTP, guanosine-5'-[beta-thio]triphosphate (GDP beta S), and 5-guanylylimidodiphosphate (GppNHp) exhibited similar potencies, inducing 52%, 46%, and 43% inhibition of [125I-Tyr4]bombesin binding respectively. Saturation experiments performed in the absence and presence of 100 microM GTP gamma S indicated the presence of a single population of receptors in both cases. However, the addition of GTP gamma S induced a marked decrease in the number of receptors (from 1.76 fmol/mg protein to 0.78 fmol/mg protein) without significantly altering the dissociation constant (Kd). These results provide evidence that bombesin receptors are coupled to a G-protein signal transduction pathway in guinea pig lung. We have further characterised this G-protein on the basis of its toxin sensitivity. Pretreatment of the lung membranes with either pertussis (10 micrograms/ml) or cholera toxin (50 micrograms/ml) was performed. Cholera toxin treatment did not affect the ability of GTP gamma S to inhibit [125I-Tyr4]bombesin binding to guinea pig lung membranes. However, pertussis toxin treatment induced a decrease in binding and resulted in the inability of GTP gamma S to inhibit [125I-Tyr4]bombesin binding in a concentration-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)
Lach
E
E
Laboratoire de Neuroimmunopharmacologie pulmonaire, INSERM CJF 91-05, Université Louis Pasteur-Strasbourg, Illkirch, France.
Trifilieff
A
A
Scherrer
D
D
Gies
J P
JP
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites / Q000187:drug effects; D001839:Bombesin / Q000378:metabolism; D002772:Cholera Toxin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006157:Guanosine Monophosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006168:Guinea Pigs; D007457:Iodine Radioisotopes; D008168:Lung / Q000378:metabolism; D008297:Male; D037342:Pertussis Toxin; D018004:Receptors, Bombesin / Q000187:drug effects / Q000378:metabolism*; D012044:Regression Analysis; D015398:Signal Transduction / Q000187:drug effects; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D006150:Guanine Nucleotides; D007457:Iodine Radioisotopes; D018004:Receptors, Bombesin; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C023427:guanosine 5'-O-(2-thiodiphosphate); D006157:Guanosine Monophosphate; D002772:Cholera Toxin; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D001839:Bombesin