periplasmic ligand-binding domain of Arabidopsis thaliana glutamate receptors and its close homologs in other plants
This group includes the ligand-binding domain of Arabidopsis thaliana glutamate receptors, which have sequence similarity with animal ionotropic glutamate receptor and its close homologs in other plants. The ligand-binding domain of GABAb receptors are metabotropic transmembrane receptors for gamma-aminobutyric acid (GABA). GABA is the major inhibitory neurotransmitter in the mammalian CNS and, like glutamate and other transmitters, acts via both ligand gated ion channels (GABAa receptors) and G-protein coupled receptors (GABAb receptor or GABAbR). GABAa receptors are members of the ionotropic receptor superfamily which includes alpha-adrenergic and glycine receptors. The GABAb receptor is a member of a receptor superfamily which includes the mGlu receptors. The GABAb receptor is coupled to G alpha-i proteins, and activation causes a decrease in calcium, an increase in potassium membrane conductance, and inhibition of cAMP formation. The response is thus inhibitory and leads to hyperpolarization and decreased neurotransmitter release, for example.
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