Dual role of protein kinase C on BK channel regulation.
Large conductance voltage- and Ca(2+)-activated potassium channels (BK channels) are important feedback regulators in excitable cells and are potently regulated by protein kinases. The present study reveals a dual role of protein kinase C (PKC) on BK channel regulation. Phosphorylation of S(695) by PKC, located between the two regulators of K(+) conductance (RCK1/2) domains, inhibits BK channel open-state probability. This PKC-dependent inhibition depends on a preceding phosphorylation of S(1151) in the C terminus of the channel alpha-subunit. Phosphorylation of only one alpha-subunit at S(1151) and S(695) within the tetrameric pore is sufficient to inhibit BK channel activity. We further detected that protein phosphatase 1 is associated with the channel, constantly counteracting phosphorylation of S(695). PKC phosphorylation at S(1151) also influences stimulation of BK channel activity by protein kinase G (PKG) and protein kinase A (PKA). Though the S(1151)A mutant channel is activated by PKA only, the phosphorylation of S(1151) by PKC renders the channel responsive to activation by PKG but prevents activation by PKA. Phosphorylation of S(695) by PKC or introducing a phosphomimetic aspartate at this position (S(695)D) renders BK channels insensitive to the stimulatory effect of PKG or PKA. Therefore, our findings suggest a very dynamic regulation of the channel by the local PKC activity. It is shown that this complex regulation is not only effective in recombinant channels but also in native BK channels from tracheal smooth muscle.
Zhou
Xiao-Bo
XB
Institute of Pharmacology for Pharmacists, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany.
Wulfsen
Iris
I
Utku
Emine
E
Sausbier
Ulrike
U
Sausbier
Matthias
M
Wieland
Thomas
T
Ruth
Peter
P
Korth
Michael
M
D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004594:Electrophysiology; D006801:Humans; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D054645:Protein Phosphatase 1 / Q000378:metabolism; D014132:Trachea / Q000166:cytology
D051036:Large-Conductance Calcium-Activated Potassium Channels; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D011493:Protein Kinase C; D054645:Protein Phosphatase 1
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