title: SOL-1 is an auxiliary subunit that modulates the gating of GLR-1 glutamate receptors in Caenorhabditis elegans.
abstract: Most rapid excitatory synaptic signaling in the brain is mediated by postsynaptic ionotropic glutamate receptors (iGluRs) that are gated open by the neurotransmitter glutamate. In Caenorhabditis elegans, sol-1 encodes a CUB-domain transmembrane protein that is required for currents that are mediated by the GLR-1 iGluR. Mutations in sol-1 do not affect GLR-1 expression, localization, membrane insertion, or stabilization at synapses, suggesting that SOL-1 is required for iGluR function. Here, we provide evidence that SOL-1 is an auxiliary subunit that modulates the gating of GLR-1 receptors. We show that mutant variants of GLR-1 with altered gating partially restore glutamate-gated current and GLR-1-dependent behaviors in sol-1 mutants. Domain analysis of SOL-1 indicates that extracellular CUB domain 3 is required for function and that a secreted variant partially restores glutamate-gated currents and behavior. Also, we show that endogenous glutamatergic synaptic currents are absent in sol-1 mutants. Our data suggest that GLR-1 iGluRs are not simply stand-alone molecules and require the SOL-1 auxiliary protein to promote the open state of the receptor. Our analysis presents the possibility that glutamatergic signaling in other organisms may be similarly modified by SOL-1-like transmembrane proteins.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Penelope J
authors.initials: PJ
authors.lastname: Brockie
authors.forename: Jerry E
authors.initials: JE
authors.lastname: Mellem
authors.forename: David M
authors.initials: DM
authors.lastname: Madsen
authors.forename: Craig S
authors.initials: CS
authors.lastname: Walker
authors.forename: Michael M
authors.initials: MM
authors.lastname: Francis
authors.forename: Andres V
authors.initials: AV
authors.lastname: Maricq
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D004594:Electrophysiology; D014644:Genetic Variation; D018698:Glutamic Acid / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D047468:Immunoprecipitation; D007700:Kinetics; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry; D008957:Models, Genetic; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D018091:Receptors, AMPA / Q000502:physiology*; D017470:Receptors, Glutamate / Q000378:metabolism; D015398:Signal Transduction; D009435:Synaptic Transmission; D013997:Time Factors; D014981:Xenopus
chemical_list: D029742:Caenorhabditis elegans Proteins; D008024:Ligands; D008565:Membrane Proteins; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; C481340:SOL-1 protein, C elegans; C096470:glr-1 protein, C elegans; D049452:Green Fluorescent Proteins; D018698:Glutamic Acid