For information on the glutamate metabotropic receptor, please see: Glutamate Metabotropic Receptor . This page is about the glutamate ionotropic receptor.
Glutamate Receptor (Wiki)
"There are two broad categories of glutamate receptors: ionotropic receptors and metabotropic receptors.
Ionotropic glutamate receptors are ligand gated ion channels whose agonists include AMPA, Kainate and NMDA. Ionotropic glutamate receptors (iGluRs) form the ion channel pore that activates when glutamate binds to the receptor.
Metabotropic glutamate receptors (mGluRs) indirectly activate ion-channels on the plasma membrane through a signaling cascade that involves G proteins. Ionotropic receptors tend to be quicker in relaying information but metabotropic are associated with a more prolonged stimulus."
"Glutamate receptors are synaptic receptors located primarily on the membranes of neuronal cells. Glutamate is one of the 20 amino acids used to assemble proteins and as a result is abundant in many areas of the body, but it also functions as a neurotransmitter and is particularly abundant in the nervous system. Glutamate receptors are responsible for the glutamate-mediated post-synaptic excitation of neural cells, and are important for neural communication, memory formation, learning, and regulation."
"Glutamate is the most prominent neurotransmitter in the body, being present in over 50% of nervous tissue. ... The two primary glutamate receptors are named after agonists that bind to them with high specificity:
AMPA (α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate) and NMDA (N-Methyl-D-Aspartate)."
"There are several compounds which are routinely used in glutamate receptor research and associated with receptor subtypes:"
A Family of Glutamate Receptor Genes (PubMed)
Abstract only online. I have PDF.
"The three glutamate receptor subunits show significant sequence conservation with the glutamine binding component of the glutamine permease of E. coli. Each of these clones encodes a channel responsive to ... AMPA."
If I understand correctly, this article concludes that the AMPA glutamate receptor, which is the most common receptor in the human nervous system, evolved from the glutamine permease of prokaryotes such as E. coli. However, this does not necessarily mean that the AMPA receptor is identical to the prokaryote glutamine permease, just that it is similar enough to support the hypothesis that the receptor evolved from the permease.
E. coli (Wiki)
"Glutamine is the most abundant naturally occurring, non-essential amino acid in the human body and one of the few amino acids which directly crosses the blood-brain barrier."
AMPA Receptors and Bacterial Periplasmic... (PubMed)
Abstract and full-length PDF.
",,,the homologous bacterial lysine/ornithine/arginine-binding protein and histidine-binding protein...Our results indicate that glutamate receptors share with the bacterial polar amino acid-binding proteins the fundamental mechanism of amino acid recognition." This article agrees that the ligand-binding of the glutamate receptor has a similar, but not identical, bacterial anticedent.
Kainate receptor - Wikipedia
"Kainate receptors, or KARs, are ionotropic receptors that respond to the neurotransmitter glutamate. They were first identified as a distinct receptor type through their selective activation by the agonist kainate, a drug first isolated from the red alga Digenea simplex. KARs are less understood than AMPA and NMDA receptors, the other ionotropic glutamate receptors. Postsynaptic kainate receptors are involved in excitatory neurotransmission. Presynaptic kainate receptors have been implicated in inhibitory neurotransmission by modulating release of the inhibitory neurotransmitter GABA through a presynaptic mechanism.