Modulation of Drosophila slowpoke calcium-dependent potassium channel activity by bound protein kinase a catalytic subunit.
Drosophila Slowpoke (dSlo) calcium-dependent potassium channels bind directly to the catalytic subunit of cAMP-dependent protein kinase (PKAc). We demonstrate here that coexpression of PKAc with dSlo in mammalian cells results in a dramatic decrease of dSlo channel activity. This modulation requires catalytically active PKAc but is not mediated by phosphorylation of S942, the only PKA consensus site in the dSlo C-terminal domain. dSlo binds to free PKAc but not to the PKA holoenzyme that includes regulatory subunits and is inactive. Activators of endogenous PKA that stimulate dSlo phosphorylation, but do not produce detectable PKAc binding to dSlo, do not modulate channel function. Furthermore, the catalytically inactive PKAc mutant does bind to dSlo but does not modulate channel activity. These results are consistent with the hypothesis that both binding of active PKAc to dSlo and phosphorylation of dSlo or some other protein are necessary for channel modulation.
Zhou
Yi
Y
Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Wang
Jing
J
Wen
Hua
H
Kucherovsky
Olga
O
Levitan
Irwin B
IB
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D020134:Catalytic Domain / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D000242:Cyclic AMP / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism; D020536:Enzyme Activators / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D051379:Mice; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D010766:Phosphorylation / Q000187:drug effects; D024681:Potassium Channels, Calcium-Activated / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D029721:Drosophila Proteins; D020536:Enzyme Activators; C494841:KCNMA1 protein, human; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; C494844:slo protein, Drosophila; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases