NMDA receptor 2B (NR2B), also known as GRIN2B, is a subunit of the NMDA receptor, a type of glutamate receptor that plays a crucial role in synaptic plasticity, learning, and memory. The NMDA receptor is a ligand-gated ion channel that allows the flow of calcium (Ca²⁺), sodium (Na⁺), and potassium (K⁺) ions into the cell in response to glutamate binding. NR2B is one of the key subunits of the receptor, contributing to its functional properties, including its ion conductance and kinetics. NR2B is predominantly expressed in the central nervous system and is particularly involved in neurodevelopmental processes and synaptic strengthening. Alterations in NR2B function have been linked to neurodegenerative diseases, psychiatric disorders, and learning impairments, making it an important target for research in these areas.