ATP-dependent activation of atrial muscarinic K+ channels in the absence of agonist and G-nucleotides
- 1 April 1990
- journal article
- research article
- Published by Springer Nature in Pflügers Archiv - European Journal of Physiology
- Vol. 416 (1-2) , 213-215
- https://doi.org/10.1007/bf00370246
Abstract
While opening of cardiac muscarinic K+ channels is mediated by a guanine nucleotide-binding protein, GK, and normally requires both ACh and cytosolic GTP, we demonstrate that in the absence of agonist and G-nucleotides guinea-pig atrial muscarinic K+ channels are activated by cytosolic ATP (K50 = 224 μM). This activation involves a phosphorylating reaction and is most probably related to a transphosphorylation by a nucleoside diphosphate kinase (NDPK) from ATP to GK-bound GDP. This ATP-induced response is completely inhibited by nanomolar concentrations of GDP or GTP, suggesting a G-nucleotide specific binding site on NDPK.Keywords
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