title: Interaction between beta-adrenergic receptors and guanine nucleotide sites in turkey erythrocyte membranes.
abstract: beta 1-Adrenergic receptors from turkey erythrocyte membranes have been identified by specific binding of the radiolabeled antagonist (-)-[3H]dihydroalprenolol. These receptors are inactivated by the alkylating agent N-ethylmaleimide when occupied by beta-adrenergic agonists but not when occupied by antagonists or when unoccupied. A time-dependent decrease of the number of receptor sites is observed. Inactivation affects 45-60% of the sites, regardless of the agonist or N-ethylmaleimide concentration. The guanine nucleotides GTP and 5'-guanylyl imidodiphosphate effectively protect the receptors against agonist-mediated inactivation by N-ethylmaleimide. Protection by ATP necessitates a 100-fold higher concentration; 10 mM NaF is ineffective. The guanine nucleotide effect is reversible and occurs via interaction with N-ethylmaleimide-insensitive sites. These observations establish that guanine nucleotide sites interact with and caused structural modification of the agonist-occupied beta-adrenergic receptors in turkey erythrocyte membranes.
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005033:Ethylmaleimide / Q000037:antagonists & inhibitors; D005459:Fluorides / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000378:metabolism* / Q000494:pharmacology; D011487:Protein Conformation; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D014422:Turkeys
chemical_list: D006150:Guanine Nucleotides; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D005033:Ethylmaleimide; D005459:Fluorides