Conserved SOL-1 proteins regulate ionotropic glutamate receptor desensitization

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Abstract
The neurotransmitter glutamate mediates excitatory synaptic transmission by activating ionotropic glutamate receptors (iGluRs). InCaenorhabditis elegans, the GLR-1 receptor subunit is required for glutamate-gated current in a subset of interneurons that control avoidance behaviors. Current mediated by GLR-1-containing iGluRs depends on SOL-1, a transmembrane CUB-domain protein that immunoprecipitates with GLR-1. We have found that reconstitution of glutamate-gated current in heterologous cells depends on three proteins, STG-1 (aC. elegansstargazin-like protein), SOL-1, and GLR-1. Here, we use genetic and pharmacological perturbations along with rapid perfusion electrophysiological techniques to demonstrate that SOL-1 functions to slow the rate and limit the extent of receptor desensitization as well as to enhance the recovery from desensitization. We have also identified a SOL-1 homologue fromDrosophilaand show thatDroSOL1 has a conserved function in promotingC. elegansglutamate-gated currents. SOL-1 homologues may play critical roles in regulating glutamatergic neurotransmission in more complex nervous systems.