Glutamate-gated receptor that probably acts as non-selective cation channel, at least in roots and hypocotyls (Probable). Can be triggered by Ala, Asn, Cys, Glu, Gly, Ser and glutathione (a tripeptide consisting of Glu-Gly-Cys) (PubMed:18162597). Mediates leaf-to-leaf wound signaling (PubMed:23969459). May be involved in light-signal transduction and calcium homeostasis via the regulation of calcium influx into cells (PubMed:17012403). Contributes to pathogen-associated molecular patterns (PAMP) elicitor-mediated resistance (PubMed:23952652). Partially involved in free cytosolic calcium variations, nitric oxide (NO) production, reactive oxygen species (ROS) production and expression of defense-related genes in response to oligogalacturonide elicitors (PubMed:23952652). Inovlved in resistance against Hyaloperonospora arabidopsidis (PubMed:23952652). Required for glutathione-induced defense responses, and innate immunity responses against the bacterial pathogen Pseudomonas syringae pv tomato strain DC3000 (PubMed:23656893). Required for the transmission of wound-induced, phloem-propagated action potential to neighbor leaves (PubMed:24716546). May form heteromers. Localizes to the plasma membrane. Expressed predominantly in roots and siliques. Impaired glutamate-triggered (and Ala, Asn, Cys, Gly, Ser and glutathione-triggered) membrane depolarization and calcium rise (PubMed:17012403, PubMed:18162597). Reduced wound-activated surface potential changes (WASP) duration in the wounded leaf, resulting in a decreased induction of the regulators of jasmonate-signaling in the systemic leaves (PubMed:23969459). Glr3.3 and glr3.6 double mutant has no detectable changes in surface potential in systemic leaves and the induction of the regulators of jasmonate-signaling is more strongly decreased (PubMed:23969459). Belongs to the glutamate-gated ion channel (TC 1.A.10.1) family.