QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Dingledine, R. Articles by Conn, P. J. Search for Related Content PubMed PubMed Citation Articles by Dingledine, R. Articles by Conn, P. J.

---

Supplement

Peripheral Glutamate Receptors: Molecular Biology and Role in Taste Sensation^{1 ,2}

Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322

³To whom correspondence should be addressed.

Glutamate is the most widespread excitatory neurotransmitter in the mammalian brain. Two classes of glutamate receptor have been cloned, the ionotropic (ligand-gated ion channels) and the metabotropic (G protein–coupled receptors). Three subclasses of ionotropic glutamate receptors are known; they are named after selective agonists, i.e., -amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), N-methyl-D-aspartate (NMDA) and kainate receptors. Fifteen functional subunits assemble together in heteromultimeric complexes to form these receptors as follows: GluR1–GluR4 for AMPA; GluR5–GluR7 and KA1-KA2 for kainate; and NR1, NR2A-NR2D and NR3 for NMDA receptors. Within a subclass, the subunit composition strongly influences the pharmacologic and biophysical properties of the receptors. The metabotropic glutamate receptors fall into the following three groups, each containing two or more individual receptor proteins: group I (mGluR1, mGluR5), group II (mGluR2, mGluR3), and group III (mGluR4, mGluR6, mGluR7 and mGluR8). In contrast to the ionotropic receptors, the metabotropic glutamate receptors appear to act as monomers or homodimers rather than heteromers. Messenger RNAs encoding several ionotropic subunits and a mGluR4-like receptor have been identified in taste buds. Although controversial, the evidence is consistent with an NMDA receptor serving as a primary taste transducer for monosodium glutamate (MSG), and a metabotropic glutamate receptor modulating the flavor-enhancing effect of MSG. Thus the neurotransmitter glutamate is intimately involved in the central processing of taste information.

KEY WORDS: • taste receptor • -amino-3-hydroxy-5-methyl-4-isoxazole propionic acid • N-methyl-D-aspartate • metabotropic • sensory transduction