Protein kinase and phosphatase modulation of quail brain GABA(A) and non-NMDA receptors co-expressed in Xenopus oocytes.
The GABA(A) receptor and the non-NMDA subtype of the ionotropic glutamate receptor were co-expressed in Xenopus oocytes by injection of quail brain mRNA. The oocytes were treated with various protein kinase (PK) and protein phosphatase (PP) activators and inhibitors and the effects on receptor functioning were monitored. Two phorbol esters, 4-beta-phorbol 12-myristate-13-acetate (PMA) and 4-beta-phorbol 12,13-dibutyrate (PDBu); the cGMP-dependent PK activators sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG); and the PP inhibitor okadaic acid (OA) reduced the amplitude of the GABA-induced currents, whilst the PK inhibitor staurosporine potentiated it. In addition, PMA, PDBu, SNP, and OA reduced the desensitization of the GABA-induced response. Identical treatments generally had similar but less pronounced effects on responses generated by kainate (KA) but the desensitization characteristic of the non-NMDA receptor was not affected. None of the treatments had any effect on the reversal potentials of the induced currents. Immunoblots revealed that the oocytes express endogenous PKG and guanylate cyclase. The results are discussed in terms of the molecular structures of GABA(A) and non-NMDA receptors and the potential functional consequences of phosphorylation/dephosphorylation.
Moon
C
C
Neurobiology Group, Department of Biology, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, London, UK.
Fraser
S P
SP
Djamgoz
M B
MB
D000818:Animals; D001923:Brain Chemistry / Q000502:physiology; D002273:Carcinogens / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D006162:Guanylate Cyclase / Q000032:analysis / Q000378:metabolism; D015151:Immunoblotting; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D019319:Okadaic Acid / Q000494:pharmacology; D009865:Oocytes / Q000502:physiology; D010703:Phorbol Esters / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D011784:Quail; D012333:RNA, Messenger / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D019311:Staurosporine / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014981:Xenopus; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D002273:Carcinogens; D006152:Cyclic GMP; D017869:Cyclic GMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D006162:Guanylate Cyclase; D009569:Nitric Oxide; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D019319:Okadaic Acid; D010703:Phorbol Esters; D010749:Phosphoprotein Phosphatases; D011494:Protein Kinases; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D018092:Kainic Acid Receptors; D019311:Staurosporine; D014665:Vasodilator Agents; D005680:gamma-Aminobutyric Acid