The ligand-binding domain of putative ionotropic glutamate receptors, a member of the type 2 periplasmic binding fold protein superfamily.
This group contains glutamate receptor domain GluR. These domains are found in the GluR proteins that have been shown to function as L-glutamate activated potassium channels, also known ionotropic glutamate receptors or iGluRs. In addition to two ligand binding core domains, iGluRs typically have a channel-like domain inserted in the middle of the GluR-like domain. Animal iGluRs mediate the ion flux in the synapses of the CNS and can be subdivided into several classes depending on the neurotransmitter specificity and ion conductance properties. Their plant homologs have been shown to function in light signal transduction and calcium homeostasis. The GluR proteins belong to the PBPII superfamily of periplasmic binding proteins that differ in size and ligand specificity, but have similar tertiary structures consisting of two globular subdomains connected by a flexible hinge. They have been shown to bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.
Jiyao W et al.(2023). "The conserved domain database in 2023.",