NR3B

NR3B, also called GluN3B, is an NMDA receptor subunit encoded by the GRIN3B gene in humans. It is a member of the ionotropic glutamate receptor family and the NR3 subfamily, which also includes GluN3A.

Function and assembly: NR3B participates in assembling with NR1 and NR2 subunits to form NMDA receptors. When incorporated, NR3B generally reduces calcium permeability and overall current through the receptor, and it can alter receptor gating, ligand sensitivity, and Mg2+/Zn2+ modulation. Receptors containing NR3B are typically less calcium-permeable than those formed from NR1/NR2 subunits alone.

Expression and regulation: GRIN3B transcripts are detected in several brain regions, with expression varying during development. Compared with NR1 and NR2 subunits, NR3B is usually expressed at lower levels.

Physiological and clinical relevance: NR3B-containing NMDA receptors are implicated in shaping synaptic plasticity and developmental processes. Changes in GRIN3B expression or function have been investigated in neurodevelopmental and psychiatric conditions, but the literature does not yet establish a consistent causal role.

Genomic and molecular notes: The GRIN3B gene undergoes alternative splicing, producing multiple isoforms with potentially distinct properties. NR3B is one of two GluN3 subunits, the other being GluN3A (GRIN3A).