Cell surface expression of GluR5 kainate receptors is regulated by an endoplasmic reticulum retention signal.
Kainate receptors (KARs) are mediators of excitatory neurotransmission in the mammalian central nervous system, and their efficient targeting and trafficking is critical for normal synaptic function. A key step in the delivery of KARs to the neuronal plasma membrane is the exit of newly assembled receptors from the endoplasmic reticulum (ER). Here we report the identification of a novel ER retention signal in the alternatively spliced C-terminal domain of the GluR5-2b subunit, which controls receptor trafficking in both heterologous cells and neurons. The ER retention motif consists of a critical arginine (Arg-896) and surrounding amino acids, disruption of which promotes ER exit and surface expression of the receptors, as well as altering their physiological properties. The Arg-896-mediated ER retention of GluR5 is regulated by a mutation that mimics phosphorylation of Thr-898, but not by PDZ interactions. Furthermore, two positively charged residues (Arg-900 and Lys-901) in the C terminus were also found to regulate ER export of the receptors. Taken together, our results identify novel trafficking signals in the C-terminal domain of GluR5-2b and demonstrate that alternative splicing is an important mechanism regulating KAR function.
Ren
Zhao
Z
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island 02912, USA.
Riley
Nathan J
NJ
Needleman
Leigh A
LA
Sanders
James M
JM
Swanson
Geoffrey T
GT
Marshall
John
J
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D019921:Biotinylation; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004594:Electrophysiology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005434:Flow Cytometry; D017353:Gene Deletion; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D018092:Kainic Acid Receptors / Q000096:biosynthesis* / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014162:Transfection
D001120:Arginine; D018092:Kainic Acid Receptors