Recombinant G-protein βγ-subunits activate the muscarinic-gated atrial potassium channel

摘要: Acetylcholine activates inwardly rectifying potassium channels (IK.ACh) in the heart through muscarinic receptor binding and activation of pertussis-toxin-sensitive G proteins. Experiments showing that only beta gamma-subunit (G gamma) IK.ACh (ref. 4) were challenged by reports activated alpha-subunit alpha) was effective. Here we examine regulation using purified brain recombinant G-protein subunits. Six gamma-subunits with apparent half-maximal concentrations 3-30 nM. Activation alpha-GTP gamma S observed, but this probably due to release GTP from protein. Importantly, activity elicited inhibited alpha-GDP, suggesting native plays a major role pathway. We conclude is primary regulator activity.