The binding capacity of [3H]-acetylcholine for muscarinic receptors of rat cerebral cortex membranes is increased in the presence of Cu2+ ions from 690 to 1320 fmol/mg protein with no significant change in affinity. Membranes treated with 50 μM Cu2+ and washed retain the increased binding capacity. Agonist binding in copper-treated membranes is insensitive to guanylylimidodiphosphate even at high concentrations (>200 μM). Similar results were obtained when the sulfhydryl oxidizing agent, diamide (2 mM) was substituted for Cu2+ in the treatment of membranes. These data suggest the involvement of inter- or intramolecular SH S-S transitions in the interaction between the muscarinic receptor and a guanine nucleotide binding regulatory protein.
|Number of pages
|Biochemical and Biophysical Research Communications
|Published - 16 Apr 1984