Created: February 13, 2022
Modified: February 13, 2022
Modified: February 13, 2022
NMDA receptor
This page is from my personal notes, and has not been specifically reviewed for public consumption. It might be incomplete, wrong, outdated, or stupid. Caveat lector.One of three types of ionotropic glutamate receptor, along with AMPA receptors and kainate receptors. It is so-called because, unlike the other glutamate receptors, it is also agonized by N-methyl-D-aspartate (NMDA).
It is permeable to sodium and calcium ions, but is ordinarily blocked by a magnesium ion (Mg2+). To open the channel, glutamate must first bind to a nearby AMPA receptor, allowing sodium ions into the cell to depolarize the membrane and release the magnesium block. If glutamate and a co-agonist---glycine or d-serine---also bind to the NMDA receptor, the channel opens, allowing calcium ions into the cell.
These calcium ions kick off intracellular signaling cascades, leading to
- additional AMPA receptors are added from internal stores to the cell membrane.
- existing AMPA receptors are phosphorylated causing them to allow even more ions through. These 'enhance' the synapse, making it more sensitive to future activation. This is thought to be one mechanism of long-term potentiation.
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