title: Antibodies raised against purified beta-adrenergic receptors specifically bind beta-adrenergic ligands.
abstract: Antibodies raised against purified beta-adrenergic receptors themselves specifically bind beta-adrenergic ligands. Digitonin-solubilized frog (Rana pipiens) erythrocyte beta-adrenergic receptors, purified 100- to 200-fold by adsorption to an alprenolol-agarose affinity support and specifically eluted from the affinity resin by 1-100 mM (+/-)-isoproterenol, were used to immunize six rabbits. All immune sera, in contrast to preimmune sera, bound the beta-adrenergic antagonist [(3)H]Dihydroalprenolol binding activity was due to immunoglobulins. By competition studies, antibody [(3)H]dihydroalprenolol binding was found to display a specificity and stereoselectivity resembling that of the beta-adrenergic receptor, [i.e., (-)-isoproterenol > (-)-epinephrine > (-)-norepinephrine; alprenolol approximately propranolol >> phentolamine = aloperidol; and (-) isomers of both agonists and antagonists 10-100 times more potent than (+) isomers]. A portion of the [(3)H]dihydroalprenolol binding antibodies could be specifically adsorbed onto purified frog erythrocyte membranes, whereas Xenopus and human erythrocyte membranes, both of which are almost devoid of beta-adrenergic receptors, were ineffective in adsorbing [(3)H]dihydroalprenolol binding antibodies. We suggest that the likely immunogen was a beta-adrenergic receptor-isoproterenol complex and that immunization with drugs noncovalently bound to their receptors might be a means of raising antibodies to biologically active otherwise nonimmunogenic small molecules. Such antibodies, whose specificity mimics that of a receptor, should also provide useful models for the study of the structure of the receptor binding sites.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000276:immunology*; D000319:Adrenergic beta-Antagonists / Q000378:metabolism*; D000818:Animals; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D001001:Anura; D001666:Binding Sites, Antibody; D004910:Erythrocyte Membrane / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology*; D006801:Humans; D007700:Kinetics; D011894:Rana pipiens; D011941:Receptors, Adrenergic / Q000276:immunology*; D011943:Receptors, Adrenergic, beta / Q000276:immunology*; D013045:Species Specificity; D014981:Xenopus
chemical_list: D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta