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Intracellular Injection of Protein Kinase Inhibitor Blocks the Serotonin-Induced Increase in K+ Conductance in Aplysia Neuron R15
William B. Adams and Irwin B. Levitan
Proceedings of the National Academy of Sciences of the United States of America
Vol. 79, No. 12, [Part 1: Biological Sciences] (Jun. 15, 1982), pp. 3877-3880
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/12735
Page Count: 4
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Previous work has shown that serotonin induces an increase in membrane K+ conductance in Aplysia neuron R15 and that this response is mediated by cAMP. The present study examines the role of protein phosphorylation in the response to serotonin. A specific inhibitor of cAMP-dependent protein kinase was injected intracellularly into neuron R15. The injection blocked the serotonin-induced increase in K+ conductance completely for at least 4 hours. The blockage was selective because the cell's response to dopamine was not inhibited. Furthermore, the blockage was specifically produced by protein kinase inhibitor because injection of other proteins (α -bungarotoxin and bovine serum albumin) did not affect the serotonin response. The serotonin response recovered fully 5-13 hours after the injection, presumably as a result of intracellular proteolysis of the protein kinase inhibitor. The results indicate that protein phosphorylation is a necessary step in the process that leads to activation of K+ channels by serotonin in neuron R15.
Proceedings of the National Academy of Sciences of the United States of America © 1982 National Academy of Sciences