Ionotropic glutamate receptors kainate receptors

Non-NMDA ionotropic glutamate receptors (the majority sodium channel containing) can be subdivided into a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) (comprising cloned subunits GluRl ) and kainate (GluR5-7, KAl-2) preferring receptors, with native receptors most likely to comprise either homo- or heteromeric pentamers of these subunits. 

Stereostructure-activity studies on agonists at the AMPA and kainate subtypes of ionotropic glutamate receptors. Chirality, 15, 167-179. 

Ionotropic glutamate receptors mediate fast excitatory neurotransmission in practically all areas of the central nervous system (CNS). They are also critical for both the induction and expression of synaptic plasticity, and have been implicated in diverse pathological conditions, such as epilepsy, ischemic brain damage, anxiety, and addiction. There are three subtypes of ionotropic glutamate receptors that are named after their high-affinity agonists as a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA), N-1nethyl-D-aspartate (NMDA), and kainate (KA) receptors (1). 

However, it is not the only mechanism, because drugs that do not work at NMDA receptors can impair memory (e.g., benzodiazepines). Other EAA receptors include the ionotropic AMPA and kainate receptors, and the metabotropic glutamate receptors (mGluR). 

There are three types of ionotropic glutamate receptors NMDA, a-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA), and kainate receptors (Fig. 1). Each is principally activated by the agonist bearing its name and is permeable to cationic flux hence, their activation results in membrane depolarization. Ionotropic glutamate receptors were originally classified based on three selective, synthetic agonists quisqualate, kainate and NMDA. After the discovery of metabotropic receptors, it became clear that quisqualate also interacts with them. Since that time, quisqualate-sensitive ionotropic receptors have been classified by the more selective agonist AMPA. 

As mentioned above, members of the superfamily of ionotropic glutamate receptors are tetramers composed out of a repertoire of at least 18 subunits. They can be categorized into three families N-methyl-D-aspartate (NMDA) receptors, a-amino-3-hydroxy-5-methyl-4-isoxazolepropioinic acid (AMPA) receptors, and kainate receptors, the two latter forming the group of non-NMDA receptors. While NMDA receptors are composed of NR1, -2 (A, B, C, and D), and -3 (A and B)... 

North RA (2002) Molecular Physiology of P2X Receptors. Physiol Rev 82 1013-67 Ohta K, Araki N, Shibata M, Komatsumoto S, Shimazu K, Fukuuchi Y (1994) Presynaptic ionotropic glutamate receptors modulate in vivo release and metabolism of striatal dopamine, noradrenaline, and 5-hydroxytryptamine involvement of both NMDA and AMPA/kainate sub-... 

Fig. 1. Domain structure of ionotropic glutamate receptors (iGluRs) showing the four major components of mammalian iGluRs and the transmembrane topology. Bacterial iGluRs do not have the ATD and the C-terminal domain, and kainate binding proteins from lower vertebrates do not have the ATD. Note that SI and S2 refer to segments of the primary sequence whereas, Lobes 1 and 2 refer to protein folding units. Both Lobes 1 and 2 are made up of pordons of both SI and S2.

The three classes of ionotropic glutamate receptors- NMDA, AMPA, and kainate- are distributed extensively throughout the MOB. NMDA receptors are found in every layer of MOB except the IPL (Watanabe et ak, 1993 Monyer et al., 1994 Petralia et al., 1994b). AMPA receptors are found in all layers except the ONL and subependymal layer (Molnar et al., 1993 Martin et al., 1993 Petralia and Wenthold, 1992 van den Pol, 1995). Kainate receptors are found in the MGL, EPL, and IPL (Monaghan and Cotman, 1982 Gall et al., 1990 Miller et al., 1990 Wisden and Seeburg, 1993). 

AMPA, kainate and NMDA ionotropic glutamate receptor expression — an in situ hybridization atlas... 

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