Cloning and characterization of chi-1: a developmentally regulated member of a novel class of the ionotropic glutamate receptor family

Ciabarra, AM; Jm, Sullivan; Gahn, L.G; Pecht, Gerlinde; Heinemann, Sabine; Sevarino, KA

doi:10.1523/jneurosci.15-10-06498.1995

Cited by 473 publications

(303 citation statements)

References 62 publications

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“…Of particular interest has been a proposed interaction of NR3 subunits with the conventional NR1/NR2 subunit combination. When coexpressed with NR1 and NR2 in Xenopus oocytes, NR3 produced a pronounced decrease in NMDA-and glutamateinduced currents compared with NR1 and NR2 alone, leading to the conclusion that either NR1/NR2/NR3 receptors form and have a lower conductance or NR3 interferes with trafficking or assembly of the NR1/NR2 receptor (9)(10)(11)(12)(13)(14). More recently, NR1 and NR3 without NR2 were found to form a glycine-gated channel in oocytes that, unlike NR1/NR2, is not blocked by extracellular Mg 2ϩ or the NMDA receptor antagonist 2-amino-5-phosphonovalerate (APV) (7).…”

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confidence: 99%

Rules of engagement for NMDA receptor subunits

Ulbrich

Isacoff²

2008

Proc. Natl. Acad. Sci. U.S.A.

150

111

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Canonical NMDA receptors assemble from two glycine-binding NR1 subunits with two glutamate-binding NR2 subunits to form glutamate-gated excitatory receptors that mediate synaptic transmission and plasticity. The role of glycine-binding NR3 subunits is less clear. Whereas in Xenopus laevis oocytes, two NR3 subunits coassemble with two NR1 subunits to form a glycine-gated receptor, such a receptor has yet to be found in mammalian cells. Meanwhile, NR1, NR2, and NR3 appear to coassemble into triheteromeric receptors in neurons, but it is not clear whether this occurs in oocytes. To test the rules that govern subunit assembly in NMDA receptors, we developed a single-molecule fluorescence colocalization method. The method focuses selectively on the plasma membrane and simultaneously determines the subunit composition of hundreds of individual protein complexes within an optical patch on a live cell. We find that NR1, NR2, and NR3 follow an exclusion rule that yields separate populations of NR1/NR2 and NR1/NR3 receptors on the surface of oocytes. In contrast, coexpression of NR1, NR3A, and NR3B yields triheteromeric receptors with a fixed stoichiometry of two NR1 subunits with one NR3A and one NR3B. At least part of this regulation of subunit stoichiometry appears to be caused by internal retention. Thus, depending on the mixture of subunits, functional receptors on the cell surface may follow either an exclusion rule or a stoichiometric combination rule, providing an important constraint on functional diversity. Cell-to-cell differences in the rules may help sculpt distinct physiological properties.NR3 ͉ total internal reflection ͉ single-molecule fluorescence ͉ subunit stoichiometry ͉ triheteromeric I on channels, receptors, and other proteins involved in transmembrane signaling are often composed of several different kinds of subunits. The composition can vary depending on the state of the cell and the availability of subunit types, which depends, in turn, on protein production and subcellular localization. Based on subunit availability and interaction affinity, complexes may form in one or more fixed stoichiometries or form with heterogeneous stoichiometries. Bulk assays may not be able to distinguish between these possibilities and could have difficulty in determining the pattern of assembly in specific subcellular compartments, in particular, separating plasma membrane fractions and intracellular membrane compartments. We used an optical approach to determine the subunit composition of integral membrane proteins complexes at the singlemolecule level. Measurements were made simultaneously for many complexes, yielding distributions from which it was possible to deduce the rule that governs complex assembly. The single-molecule approach is compatible with normal (low) levels of protein expression, where the formation of nonnative highorder complexes and aggregation are avoided.Our technique is based on the colocalization of single subunits of a macromolecular complex that are fused to fluorescent protein (FP) tags ...

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confidence: 99%

Rules of engagement for NMDA receptor subunits

Ulbrich

Isacoff²

2008

Proc. Natl. Acad. Sci. U.S.A.

150

111

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“…NMDAR can contain two classes of subunits, NR1 and NR2 (A-D). The third class of subunits (NR3), containing NR3A and NR3B, is thought to act as modulators of the NMDAR (Ciabarra et al, 1995;Nishi et al, 2001; for review see Cull-Candy, 2001). A functional NMDAR appears to consist of two NR1 subunits and two or three NR2 subunits.…”

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“…For example, NR2A-containing NMDAR promote, whereas NR2B-containing NMDAR inhibit, the surface expression of GluR1 (Kim et al, 2005). In addition, a third NMDAR subunit, NR3, could regulate NMDAR transmission in mammalian motoneurons (Ciabarra et al, 1995;Nishi et al, 2001). It is not known whether NR3 is found outside mammals.…”

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confidence: 99%

Development of NMDA R1 expression in chicken auditory brainstem

Tang

Carr

2004

Hearing Research

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N-methyl-D-aspartate (NMDA) receptor subunit-specific probes were used to characterize developmental changes in the distribution of excitatory amino acid receptors in the chicken's auditory brainstem nuclei. Although NR1 subunit expression does not change greatly during the development of the cochlear nuclei in the chicken Hear. , there are significant developmental changes in NR2 subunit expression. We used in situ hybridization against NR1, NR2A, NR2B, NR2C, and NR2D to compare NR1 and NR2 expression during development. All five NMDA subunits were expressed in the auditory brainstem before embryonic day (E) 10, when electrical activity and synaptic responses appear in the nucleus magnocellularis (NM) and the nucleus laminaris (NL). At this time, the dominant form of the receptor appeared to contain NR1 and NR2B. NR2A appeared to replace NR2B by E14, a time that coincides with synaptic refinement and evoked auditory responses. NR2C did not change greatly during auditory development, whereas NR2D increased from E10 and remained at fairly high levels into adulthood. Thus changes in NMDA NR2 receptor subunits may contribute to the development of auditory brainstem responses in the chick. Indexing termscochlear nucleus; magnocellularis; laminaris; angularis; tonotopic gradient Physiological studies have shown that the auditory system is characterized by fast, accurate encoding of auditory information (Warchol and Dallos, 1990; Zhang and Trussell, 1994a,b;Fukui and Ohmori, 2003). We have therefore investigated the distribution of subtypes of Nmethyl-D-aspartate (NMDA) receptors (NMDAR) in the brainstem auditory nuclei of the chicken to determine whether changes in receptors may reflect the development of specializations for temporal processing. NMDAR can contain two classes of subunits, NR1 and NR2 (A-D). The third class of subunits (NR3), containing NR3A and NR3B, is thought to act as modulators of the NMDAR (Ciabarra et al., 1995;Nishi et al., 2001; for review see Cull-Candy, 2001). A functional NMDAR appears to consist of two NR1 subunits and two or three NR2 subunits. NR1 is the fundamental subunit necessary for the NMDAR complex, and its expression is spatiotemporally ubiquitous compared with that of NR2 subunits in vertebrate brain (Watanabe et al., 1992;Wada et al., 2004).Changes in NMDAR composition characterize the development of forebrain circuits. NR2B has been shown to be necessary for synapse formation and plasticity (Tang et al., 1999;Slutsky et al., 2004), whereas NR2A expression is associated with synaptic maturation (Fu et al., 2005). NMDAR made up of NR2B and NR1 subunits are the dominant form during NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript the "critical period" window for plasticity in mouse visual cortex (Quinlan et al., 1999a) and barrel cortex ) and in vocal learning regions of songbirds (Basham et al., 1999;Singh et al., 2000;Ding and Perkel, 2004). Near the end of the critical period, there is a gradual increase in the contribution of NR2A subunits i...

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“…It has been postulated that glutamate taste is transduced, in part, by glutamate receptors (GluRs) similar to those found in the brain (Faurion, 1991;Akabas, 1993). Ionotropic glutamate receptors (iGluRs) in the brain include ion channels selectively activated by AMPA, kainate (KA), NMDA; and KA-binding subunits; and the poorly understood 6 and x receptors (Hollmann and Heinemann, 1994;Ciabarra et al, 1995). The subunits for these receptors are characterized by four transmembrane helices and are related distantly to ionotropic receptors for other neurotransmitters.…”

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The Taste of Monosodium Glutamate: Membrane Receptors in Taste Buds

et al. 1996

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Receptor proteins for photoreception have been studied for several decades. More recently, putative receptors for olfaction have been isolated and characterized. In contrast, no receptors for taste have been identified yet by molecular cloning. This report describes experiments aimed at identifying a receptor responsible for the taste of monosodium glutamate (MSG). Using reverse transcriptase (IV)-PCR, we found that several ionotropic glutamate receptors are present in rat lingual tissues. However, these receptors also could be detected in lingual tissue devoid of taste buds. On the other hand, RT-PCR and RNase protection assays indicated that a G-protein-coupled metabotropic glutamate receptor, mGluR4, also is expressed in lingual tissues and is limited only to taste buds. In situ hybridization demonstrated that mGluR4 is detectable in 40-70% of vallate and foliate taste buds but not in surrounding nonsensory epithelium, confirming the localization of this metabotropic receptor to gustatory cells. Expression of mGluR4 in taste buds is higher in preweaning rats compared with adult rats. This may correspond to the known higher sensitivity to the taste of MSG in juvenile rodents. Finally, behavioral studies have indicated that MSG and L-2-amino-4-phosphonobutyrate (L-AP4), a ligand for mGluR4, elicit similar tastes in rats. We conclude that mGluR4 may be a chemosensory receptor responsible, in part, for the taste of MSG.

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Cloning and characterization of chi-1: a developmentally regulated member of a novel class of the ionotropic glutamate receptor family

Cited by 473 publications

References 62 publications

Rules of engagement for NMDA receptor subunits

Rules of engagement for NMDA receptor subunits

Development of NMDA R1 expression in chicken auditory brainstem

The Taste of Monosodium Glutamate: Membrane Receptors in Taste Buds

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