DmGluRA, a Drosophila metabotropic glutamate receptor, activates G-proteininwardly rectifying potassium channels in Xenopus oocytes

Xenopus oocytes were coinjected with cDNAs encoding the Drosophila melanoga ster metabotropic glutamate receptor (DmGluRA) and two mammalian G-protein inwardly rectifying potassium channel subunits (GIRK1 and GIRK2). Glutamate and two vertebrate group II mGluR agonists (order of potency: LY 354740 > glutamate > DCG IV) elicited inwardly rectifying potassium currents. These inward currents were sensitive to cesium and barium. They were also blocked by two group II specific antagonists MCCG and APICA (IC(50)s 97.5 and 200 mu M, respectively) and not affected by a group I antagonist (AIDA). Final ly, the A-protomer of PTX reduced the glutamate-induced GIRK currents. Th i s study is the first characterization of an invertebrate mGluR-mediated GIR K currents via a PTX-sensitive G protein. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.