title: Effect of pertussis toxin on alpha 2-adrenoceptors: decreased formation of the high-affinity state for agonists.
abstract: Administration of pertussis toxin to hamsters abolishes the alpha 2-adrenergic inhibition of adenylate cyclase in their adipocytes. The toxin did not modify the number of adipocyte alpha 2-adrenoceptors or their affinity for antagonists. In contrast, the affinity for agonists was significantly diminished in adipocyte membranes obtained from pertussis toxin-treated hamsters as compared to the controls. This decrease in affinity was due to a significant diminution in the proportion of sites displaying the high-affinity state for agonists. It is concluded that pertussis toxin induces a shift in the proportion of sites in high- and low-affinity states. for agonists towards the low-affinity conformation.
mesh_terms: D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D001667:Binding, Competitive; D006224:Cricetinae; D004088:Dihydroergotoxine / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008647:Mesocricetus; D037342:Pertussis Toxin; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000378:metabolism; D010566:Virulence Factors, Bordetella
chemical_list: D037361:Adenylate Cyclase Toxin; D001427:Bacterial Toxins; D011942:Receptors, Adrenergic, alpha; D010566:Virulence Factors, Bordetella; D004088:Dihydroergotoxine; D006165:Guanylyl Imidodiphosphate; D000324:Adrenocorticotropic Hormone; D037342:Pertussis Toxin; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D004837:Epinephrine