Enables NMDA glutamate receptor activity; calcium channel activity; and neurotransmitter receptor activity involved in regulation of postsynaptic membrane potential. Involved in negative regulation of dendritic spine maintenance and positive regulation of neuron death. Acts upstream of or within several processes, including behavioral fear response; detection of mechanical stimulus involved in sensory perception of pain; and learning or memory. Located in several cellular components, including cytoplasmic vesicle; lysosome; and synaptic membrane. Part of NMDA selective glutamate receptor complex. Is active in glutamatergic synapse. Is integral component of postsynaptic density membrane. Is expressed in several structures, including adipose tissue; central nervous system; eye; gut; and reproductive system. Human ortholog(s) of this gene implicated in several diseases, including alcohol use disorder; autosomal dominant non-syndromic intellectual disability 6; bipolar disorder; developmental and epileptic encephalopathy 27; and neurodegenerative disease (multiple). Orthologous to human GRIN2B (glutamate ionotropic receptor NMDA type subunit 2B). [provided by Alliance of Genome Resources, Apr 2022]