Why the study?
Does the alpha subunit or the beta gamma subunit of G proteins physiologically activate muscarinic potassium channels in atrial cells?
Does the alpha subunit or the beta gamma subunit of G proteins physiologically activate muscarinic potassium channels in atrial cells?
The alpha subunit of G proteins physiologically activates muscarinic potassium channels in the atrium, requiring much lower concentrations than the beta gamma dimer.
Answers are grounded in this paper and cite their sources.
Alpha subunit potency favors its physiological role in atrial K+ channels; leaves open human translation and clinical relevance.
It has been debated whether the potassium channel of the atrium is activated by the alpha subunit or by the beta gamma subunits of guanine nucleotide binding (G) proteins, which dissociate on activation with guanosine triphosphate (GTP). Therefore, the channel-activating effectiveness of these subunits on isolated guinea pig atrial cells was tested. The activated alpha K subunit from human erythrocytes activated the channel in subpicomolar concentrations. The beta gamma dimer from bovine brain activated the channel in nanomolar concentrations. These results support the view that, physiologically, the alpha subunit activates the channel.
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Cerbai et al. (1988) studied this question.
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