The N-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA and kainate receptors. Depending on its subunit composition, its ligands are glutamate and glycine (or D-serine). However, the binding of the ligands is typically not sufficient to open the channel as it may be blocked by Mg2+ ions which are only removed when the neuron is sufficiently depolarized. Thus, the channel acts as a “coincidence detector” and only once both of these conditions are met, the channel opens and it allows positively charged ions (cations) to flow through the cell membrane. The NMDA receptor is thought to be very important for controlling synaptic plasticity and mediating learning and memory functions. Activation of NMDA receptors results in the opening of the ion channel that is nonselective to cations, with a combined reversal potential near 0 mV. While the opening and closing of the ion channel is primarily gated by ligand binding, the current flow through the ion channel is voltage-dependent. Extracellular magnesium (Mg2+) and zinc (Zn2+) ions can bind to specific sites on the receptor, blocking the passage of other cations through the open ion channel. Depolarization of the cell dislodges and repels the Mg2+ and Zn2+ ions from the pore, thus allowing a voltage-dependent flow of sodium (Na+) and calcium (Ca2+) ions into the cell and potassium (K+) out of the cell. Functional NMDA receptors are heterotetramers composed of two GluN1 and typically two GluN2 subunits. While a single GluN2 subunit is found in invertebrate organisms, four distinct isoforms of the GluN2 subunit are expressed in vertebrates and are referred to with the nomenclature GluN2A through GluN2D (encoded by GRIN2A, GRIN2B, GRIN2C, GRIN2D). This is a model of the mouse GRIN2B receptor built by using models from Alphafold database and a membrane bilayer.
#molecularart ... #immolecular ... #glutamate ... #receptor ... #neuron ... #GRIN2B ... #heterotetramer ... #alphafold
Rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #glutamate ... #receptor ... #neuron ... #GRIN2B ... #heterotetramer ... #alphafold
Rendered with @proteinimaging and depicted with @corelphotopaint
