Glutamate receptor ionotropic, NMDA 1 subunit (GluN1)

The **glutamate receptor ionotropic, NMDA 1 subunit**—commonly called GluN1 or NR1—is an essential component of the N-methyl-D-aspartate (**NMDA**) type glutamate receptors. These receptors are heterotetrameric ligand-gated cation channels found throughout the central nervous system. The functional NMDA receptor requires two obligatory GluN1 subunits combined with two regulatory subunits from either the GluN2 or GluN3 families. Activation requires simultaneous binding of glutamate to a regulatory site and glycine/D-serine to a site on each GluN1 unit. Once activated—and after relief from voltage-dependent magnesium block—the channel allows calcium as well as sodium influx into neurons, triggering downstream signaling critical for synaptic plasticity, learning, memory formation, and excitatory neurotransmission. Dysfunctional regulation has been implicated in numerous neurological diseases including epilepsy, schizophrenia, neurodegeneration following stroke/ischemia ("excitotoxicity"), chronic pain states, and certain autoimmune encephalitides. Several clinically important drugs—including memantine and ketamine—target this complex through various mechanisms such as noncompetitive antagonism within its pore region.

Other names

N-methyl-D-aspartate receptor subunit 1NR1GluN1GRIN1 (gene symbol)

Drugs targeting this molecule typically act by one or more of these mechanisms: - Noncompetitive antagonism at the channel pore, blocking Ca²⁺ influx after activation by glutamate/glycine. - Competitive antagonism at glutamate or glycine binding sites. - Allosteric modulation via other ligand-binding domains.