TABLE 2Ionotropic Glutamate Receptor Subunit Composition

AMPAaNMDAbKainatec
GluR1 (GluA1, GluRA)NR1 (GluN1)GluR5 (GluK1)
GluR2 (GluA2, GluRB)NR2A (GluN2A)GluR6 (GluK2)
GluR3 (GluA3, GluRC)NR2B (GluN2B)GluR7 (GluK3)
GluR4 (GluA4, GluRD)NR2C (GluN2C)KA1 (GluK4)
NR2D (GluN2D)KA2 (GluK5)
NR3A (GluN3A)
NR3B (GluN3B)
a

AMPA receptor subunits can form a functional channel either by themselves or combined with other subunits. The channel is permeable to Na+, K+, and Ca2+ when a GluR2 subunit is absent, but only to Na+ and K+ when GluR2 is present.

b

All NMDA receptors contain two glycine-binding NR1 subunits and the channel is permeable to Na+, K+, and Ca2+. Incorporation of two glutamate-binding NR2 subunits allows channel opening upon the binding of glutamate. NR3 subunits bind glycine and, if combined with NR1, may create a novel type of glycine receptor. NR1/NR2/NR3 combinations are also possible. The role of NR3 subunits in glutamate synaptic function is unclear.

c

GluR5, GluR6, or GluR7 subunits or any combination of the three can form a functional channel with low agonist affinity. Incorporation of KA1 or KA2 into the complex forms a channel with high agonist affinity. Neither KA1 nor KA2 can form a homomeric channel.

From: Plasticity of Glutamate Synaptic Mechanisms

Cover of Jasper's Basic Mechanisms of the Epilepsies
Jasper's Basic Mechanisms of the Epilepsies [Internet]. 4th edition.
Noebels JL, Avoli M, Rogawski MA, et al., editors.
Copyright © 2012, Michael A Rogawski, Antonio V Delgado-Escueta, Jeffrey L Noebels, Massimo Avoli and Richard W Olsen.

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