Palmitoylation of the GluR6 kainate receptor.
The G-protein-coupled metabotropic glutamate receptor mGluR1 alpha and the ionotropic glutamate receptor GluR6 were examined for posttranslational palmitoylation. Recombinant receptors were expressed in baculovirus-infected insect cells or in human embryonic kidney cells and were metabolically labeled with [3H]palmitic acid. The metabotropic mGluR1 alpha receptor was not labeled whereas the GluR6 kainate receptor was labeled after incubation with [3H]palmitate. The [3H]palmitate labeling of GluR6 was eliminated by treatment with hydroxylamine, indicating that the labeling was due to palmitoylation at a cysteine residue via a thioester bond. Site-directed mutagenesis was used to demonstrate that palmitoylation of GluR6 occurs at two cysteine residues, C827 and C840, located in the carboxyl-terminal domain of the molecule. A comparison of the electrophysiological properties of the wild-type and unpalmitoylated mutant receptor (C827A, C840A) showed that the kainate-gated currents produced by the unpalmitoylated mutant receptor were indistinguishable from those of the wild-type GluR6. The unpalmitoylated mutant was a better substrate for protein kinase C than the wild-type GluR6 receptor. These data indicate that palmitoylation may not modulate kainate channel function directly but instead affect function indirectly by regulating the phosphorylation state of the receptor.
Pickering
D S
DS
Medical Research Council Group on Nerve Cells and Synapses, University of Toronto, ON, Canada.
Taverna
F A
FA
Salter
M W
MW
Hampson
D R
DR
D000409:Alanine; D000818:Animals; D001345:Autoradiography / Q000379:methods; D001483:Base Sequence; D002460:Cell Line; D003545:Cysteine; D018076:DNA, Complementary; D004622:Embryo, Mammalian; D004625:Embryo, Nonmammalian; D006801:Humans; D007668:Kidney; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D016366:Open Reading Frames; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D011493:Protein Kinase C / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D018092:Kainic Acid Receptors / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D018411:Spodoptera; D014162:Transfection; D014316:Tritium; D000097806:GluK2 Kainate Receptor
D000409:Alanine; D003545:Cysteine; D018076:DNA, Complementary; D009838:Oligodeoxyribonucleotides; D019308:Palmitic Acid; D010169:Palmitic Acids; D011493:Protein Kinase C; D018092:Kainic Acid Receptors; D018094:Receptors, Metabotropic Glutamate; D011994:Recombinant Proteins; D014316:Tritium; D000097806:GluK2 Kainate Receptor