title: Parallel inactivation of alpha 2-adrenergic agonist binding and Ni by alkaline treatment.
abstract: Alpha 2-Adrenergic receptor-mediated inhibition of adenylate cyclase requires the guanine nucleotide-binding protein, Ni. This protein may also be required for stabilization of high-affinity alpha 2-adrenergic agonist binding. Human platelet membranes treated under alkaline conditions (pH 11.5) exhibited a selective loss of high-affinity agonist binding as measured by p-[3H]aminoclonidine and [3H]UK 14,304. Binding of the antagonist [3H]yohimbine was largely unaffected with retention of greater than 60% of control binding sites. Ni, determined by pertussis toxin-catalyzed [32P]ADP-ribosylation of cholate extracts from alkaline-treated membranes, was also markedly reduced. The parallel loss of alpha 2-agonist binding and Ni provides additional evidence that Ni is required for alpha 2-adrenergic agonist binding.
mesh_terms: D037361:Adenylate Cyclase Toxin; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009243:NAD / Q000097:blood; D037342:Pertussis Toxin; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000378:metabolism
chemical_list: D037361:Adenylate Cyclase Toxin; D011942:Receptors, Adrenergic, alpha; D010566:Virulence Factors, Bordetella; D009243:NAD; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins