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The N-methyl-D-aspartate (NMDA) receptor channels cross a neuron's membrane and allow calcium ions to enter the cell when the channels are open (Bliss). Therefore, due to their involvement in synaptic transmission and long-term potentiation (LTP), these receptors are believed to be involved in learning and memory (Bliss). The receptors are made of various subunits with one always being NMDAR1 and the other being one of the NMDAR2 subunits (Bliss). NMDA 2B subunits are of interest because they are located in the hippocampus and because 2B subunits are replaced by 2A subunits in adult brains (Bliss).
Figure 1: The NMDA receptor complex.
Picture and Explanation from National Institute on Alcohol Abuse and Alcholism Website
"Activation or excitation occurs when either glutamate (Glu) or N-methyl-d-aspartate (NMDA) and glycine (Gly) bind to the receptor molecule. A channel within the receptor complex enables molecules to cross the cell membrane. Magnesium (Mg) blocks this channel. When Mg is removed from the channel and the receptor is activated, calcium (Ca++) and sodium (Na+) ions enter the cell and potassium ions (K+) leave. MK-801 prevents the flow of ions across the membrane by binding to a site within the ion channel, thereby blocking NMDA receptor function and protecting the cell against excess activation" (<http://www.niaaa.nih.gov/gallery/neuroscience/221p51.htm>).
NMDAR1-(NMDA Receptor 1)
Figure 2: Transmembrane Segment 2 Of NMDA Receptor 1
NMR picture from PDB Website
The NMDAR1 subunit is also believed to have a role in learning and memory,
but conclusive studies have not been performed to my knowledge. See the OMIM
website for more information on this subunit.
NMDA Receptor Subunit 2B
This subunit of the NMDA receptor is the focus of Tang et. al.'s study. Go back to read my summary of the article or click on the links below to learn lots of information about this receptor subunit.
Everything you need to know about the NR2B: OMIM Info.
NR2B mRNA Sequence
NR2B Protein Sequence
Human NR2B vs. Mouse NR2B Alignment
Human--Chromosome 12 Ideogram
More NR2B Information: Locus Link
Bliss, T.V.P. September 1999. "Young Receptors Make Smart Mice." Nature. 401: 25-27.
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