N-terminal leucine/isoleucine/valine-binding protein (LIVBP)-like domain of the ionotropic N-methyl-d-asparate (NMDA) subtype of glutamate receptors
N-terminal leucine/isoleucine/valine-binding protein (LIVBP)-like domain of the ionotropic N-methyl-d-asparate (NMDA) subtype of glutamate receptors. While this N-terminal domain belongs to the periplasmic-binding fold type I superfamily, the glutamate-binding domain of the iGluR is structurally homologous to the periplasmic-binding fold type II. The LIVBP-like domain of iGluRs is thought to play a role in the initial assembly of iGluR subunits, but it is not well understood how this domain is arranged and functions in intact iGluR. The function of the NMDA subtype receptor serves critical functions in neuronal development, functioning, and degeneration in the mammalian central nervous system. The functional NMDA receptor is a heterotetramer comprising two NR1 and two NR2 (A, B, C, and D) or NR3 (A and B) subunits. The receptor controls a cation channel that is highly permeable to monovalent ions and calcium and exhibits voltage-dependent inhibition by magnesium. Dual agonists, glutamate and glycine, are required for efficient activation of the NMDA receptor. Among NMDA receptor subtypes, the NR2B subunit containing receptors appear particularly important for pain perception; thus NR2B-selective antagonists may be useful in the treatment of chronic pain.