Modulation of a cloned mouse brain potassium channel.
The mouse brain K+ channel (MBK), previously cloned by others, has been independently cloned and shown to express in Xenopus oocytes. This K+ current (IK) inactivated over a time course of seconds and was sensitive to the K+ channel-blocking reagent tetraethylammonium. When the K+ channel was coexpressed with a cloned mouse brain serotonin receptor (5HT1c) in oocytes, activation of the 5HT1c receptor by a brief application of serotonin resulted in a suppression of the IK amplitude over the next 20 min. IK could also be suppressed by activation of G proteins. Suppression was also caused by intracellular Ca2+ injections and was blocked by intracellular injection of EGTA. Calmodulin antagonists block the IK suppression, but a known protein kinase inhibitor did not block suppression. The 5HT1c suppression was reversible; recovery from suppression was blocked by the protein kinase inhibitor H-7. These data suggest that the IK suppression occurs through a novel mechanism independent of A- or C-type protein kinases; suppression is best explained as being due to the action of a Ca2+/calmodulin-activated phosphatase; recovery from suppression is due to the action of a protein kinase.
Hoger
J H
JH
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.
Walter
A E
AE
Vance
D
D
Yu
L
L
Lester
H A
HA
Davidson
N
N
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D003001:Cloning, Molecular; D004594:Electrophysiology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000502:physiology; D007425:Intracellular Membranes / Q000378:metabolism; D051379:Mice; D009712:Nucleotides, Cyclic / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000502:physiology; D011985:Receptors, Serotonin / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology; D014982:Xenopus laevis
D009712:Nucleotides, Cyclic; D015221:Potassium Channels; D011985:Receptors, Serotonin; D012701:Serotonin; D011494:Protein Kinases; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D002118:Calcium