title: A C-terminal determinant of GluR6 kainate receptor trafficking.
abstract: Intracellular trafficking of ionotropic glutamate receptors is regulated predominantly by determinants in the cytoplasmic C-terminal domain of the subunit proteins. Although AMPA receptors are found at the vast majority of excitatory synapses, synaptic kainate receptors exhibit a much more restricted distribution, suggesting that specific mechanisms exist for selective trafficking of these receptor proteins. In this report, we define a critical forward trafficking motif that is necessary for surface expression of the glutamate receptor 6 (GluR6) kainate receptor as well as chimeric proteins containing only the GluR6 C-terminal domain. The trafficking determinant was identified by tracking surface expression of green fluorescent protein-tagged GluR6 receptors with confocal immunofluorescence in COS-7 cells and cultured neurons and patch-clamp electrophysiology in human embryonic kidney 293 cells. Serial truncation and alanine site mutagenesis of the GluR6 subunit C terminus localized the critical motif to a seven amino acid stretch of predominantly basic residues. Alanine mutation of the trafficking motif reduced kainate receptor current amplitudes by >90% and resulted in retention of the mutated receptors in the endoplasmic reticulum. This forward trafficking domain is the first such identified for kainate receptors.
authors.affiliation: Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Yan
authors.forename: James M
authors.initials: JM
authors.lastname: Sanders
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: Yongling
authors.initials: Y
authors.lastname: Zhu
authors.forename: Anis
authors.initials: A
authors.lastname: Contractor
authors.forename: Geoffrey T
authors.initials: GT
authors.lastname: Swanson
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D018698:Glutamic Acid / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018092:Kainic Acid Receptors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D000097806:GluK2 Kainate Receptor
chemical_list: D018698:Glutamic Acid; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D021122:Protein Subunits; D018092:Kainic Acid Receptors; D011993:Recombinant Fusion Proteins; D000097806:GluK2 Kainate Receptor