title: Specific uncoupling by islet-activating protein, pertussis toxin, of negative signal transduction via alpha-adrenergic, cholinergic, and opiate receptors in neuroblastoma x glioma hybrid cells.
abstract: Exposure of NG108-15 hybrid cells to islet-activating protein (IAP), pertussis toxin, caused strong ADP-ribosylation of one of the membrane proteins with a molecular weight of 41,000. This ADP-ribosylation was paralleled by decreases in the inhibition of cAMP accumulation in intact cells or associated with reversal of the inhibition of GTP-dependent membrane adenylate cyclase, via alpha-adrenergic, cholinergic muscarinic, or opiate receptors. The affinity of these receptors for agonists was lowered by guanyl-5'-yl beta-gamma-imidodiphosphate (Gpp(NH)p) reflecting their coupling to the guanine nucleotide regulatory protein in this cell line. This effect of Gpp(NH)p was lost in membranes of IAP-treated cells; in the absence of Gpp(NH)p, the affinity for agonist was lower in treated than in nontreated cells. In contrast, the function of these receptors to bind antagonists remained unaltered in IAP-treated cells. Thus, IAP treatment of NG108-15 cells caused specific uncoupling of negative signal transduction from inhibitory receptors to the adenylate cyclase catalytic unit via the guanine nucleotide regulatory protein, as a result of ADP-ribosylation of one of the subunits of the regulatory protein.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D037361:Adenylate Cyclase Toxin; D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D005910:Glioma; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006822:Hybrid Cells / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009447:Neuroblastoma; D037342:Pertussis Toxin; D051381:Rats; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*; D010566:Virulence Factors, Bordetella
chemical_list: D037361:Adenylate Cyclase Toxin; D001426:Bacterial Proteins; D008565:Membrane Proteins; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011950:Receptors, Cholinergic; D011957:Receptors, Opioid; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D006165:Guanylyl Imidodiphosphate; D000242:Cyclic AMP; D037342:Pertussis Toxin