Key result
Atropine dissociates myocardial muscarinic receptor-G protein complexes following agonist removal.
Why the study?
The stability and dissociation mechanisms of muscarinic acetylcholine receptor and G protein complexes in heart membranes were not directly demonstrated.
This study provides the first direct demonstration that the binding of an antagonist (atropine) destabilizes receptor-G protein complexes in heart membranes.
Antagonist destabilization of cardiac muscarinic receptor-G protein complexes may modulate signaling; leaves open in vivo relevance and requires cellular validation.
Complexes of muscarinic acetylcholine receptor and guanine nucleotide-binding protein (G protein) are formed in the presence of the agonist carbachol. The complexes remain stable after removal of agonist, and survive subsequent solubilization from cardiac membranes and purification. Dissociation of the receptor from the G protein occurs when the antagonist atropine is added following removal of agonist. This is the first direct demonstration of destabilization of receptor-G protein complexes by the binding of an antagonist.
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Matesic et al. (1991) studied this question. Atropine was evaluated on Dissociation of receptor-G protein complexes. Atropine dissociates complexes of muscarinic acetylcholine receptor and G protein in heart membranes following the removal of the agonist carbachol.
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