Modulation by protein kinase A of a cloned rat brain potassium channel expressed in Xenopus oocytes.
A potassium channel from rat brain was expressed in Xenopus oocytes in order to study modulation of channel function by phosphorylation via protein kinase A. Application of 8-Br-cAMP to oocytes expressing the drk1 channel (with the first 139 amino acids of the N terminus deleted, delta Ndrk1) caused a voltage-independent elevation of current amplitude, which was not seen for endogenous currents or for wild-type full-length drk1 channel. This effect on delta Ndrk1 was blocked by pre-injection of oocytes with Walsh-peptide protein kinase A inhibitor, suggesting mediation via protein kinase A. The protein kinase inhibitor also reduced both delta Ndrk1 and full-length drk1 currents. Substitution of the serine residues by alanine at one or both of the two consensus protein kinase A phosphorylation sites on the C terminus (residues 440 and 492) of delta Ndrk1 resulted in a loss of function of the expressed channels. These results indicate that phosphorylation via protein kinase A modulates drk1 channel function and that both consensus phosphorylation sites seems to be essential for channels to function.
Department of Pharmacology, University of Leeds, UK.
G G
GG
Wilson
C A
CA
O'Neill
A
A
Sivaprasadarao
J B
JB
Findlay
D
D
Wray
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D003001:Cloning, Molecular; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051668:Delayed Rectifier Potassium Channels; D005260:Female; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D017354:Point Mutation; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary / Q000494:pharmacology*; D051381:Rats; D014982:Xenopus laevis
D051668:Delayed Rectifier Potassium Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; D015124:8-Bromo Cyclic Adenosine Monophosphate; D017868:Cyclic AMP-Dependent Protein Kinases