Modulation of glycine-activated ion channel function by G-protein βγ subunits

Yévenes, Gonzalo E.; Peoples, Robert W.; Tapia, Juan Carlos; Parodí, Jorge; Soto, Ximena; Olate, Juan; Aguayo, Luis G.

doi:10.1038/nn1095

Cited by 90 publications

(116 citation statements)

References 43 publications

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“…1A). As previously reported (16), the amplitude of the glycine-activated current in human wild type GlyRs was strongly enhanced above control (80 Ϯ 10%, n ϭ 18) after 15 min of intracellular dialysis with GTP␥S (Fig. 1, B and C).…”

Section: Effects Of G Protein Activation On Wild Type and Truncatedsupporting

confidence: 87%

“…Electrophysiology-Whole cell recordings were performed as previously described (16,38). A holding potential of Ϫ60 mV was used.…”

Section: Methodsmentioning

confidence: 99%

“…For G protein activation experiments, GTP␥S (0.5 mM) was added directly to the internal solution, replacing GTP. The amplitude of the glycine current was assayed using a short (1-2 s) pulse of 30 -40 M glycine every 60 s as previously described (16). Strychnine (1 M) blocked all of the current elicited by wild type and mutant glycine receptors (not shown).…”

Section: Methodsmentioning

confidence: 99%

“…It is known that G␤␥ overexpression can induce tonic modulation of Ca ϩ2 , GIRK channels, and GlyRs (16,26,27). Therefore, we examined the ability of wild and mutant GlyRs to display this phenomenon.…”

Section: Effects Of G Protein Activation On Wild Type and Truncatedmentioning

confidence: 99%

“…This involves specific serine residues in the loop between transmembrane domains 3 and 4 (6, 10 -14). On the other hand, recent reports have shown that the activity of GlyRs and nAChRs can be modulated by G protein ␤␥ subunits in a phosphorylation-independent manner (15,16). In both cases, activation of G proteins, using nonhydrolyzable GTP analogs or by application of purified G␤␥ dimers, generates a strong enhancement in the agonist-evoked current, related to a shift to the left in the agonist concentration-response curve and an increased open channel probability (15,16).…”

mentioning

confidence: 99%

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Molecular Determinants for G Protein βγ Modulation of Ionotropic Glycine Receptors

Yévenes

Moraga-Cid

Guzmán

et al. 2006

Journal of Biological Chemistry

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The ligand-gated ion channel superfamily plays a critical role in neuronal excitability. The functions of glycine receptor (GlyR) and nicotinic acetylcholine receptor are modulated by G protein ␤␥ subunits. The molecular determinants for this functional modulation, however, are still unknown. Studying mutant receptors, we identified two basic amino acid motifs within the large intracellular loop of the GlyR ␣ 1 subunit that are critical for binding and functional modulation by G␤␥. Mutations within these sequences demonstrated that all of the residues detected are important for G␤␥ modulation, although both motifs are necessary for full binding. Molecular modeling predicts that these sites are ␣-helixes near transmembrane domains 3 and 4, near to the lipid bilayer and highly electropositive. Our results demonstrate for the first time the sites for G protein ␤␥ subunit modulation on GlyRs and provide a new framework regarding the ligand-gated ion channel superfamily regulation by intracellular signaling.The ionotropic glycine receptors (GlyRs) 2 are members of the ligand-gated ion receptor superfamily, which includes inhibitory ␥-aminobutyric acid type A receptors and excitatory nAChR and 5-HT 3 receptors. These homologous receptors mediate fast synaptic transmission in the central nervous system (1, 2). Inhibitory GlyRs are critical for the control of excitability in the mammalian spinal cord and brain stem. Binding of glycine to the extracellular region induces a rapid increase in Cl Ϫ ion conductance, generating a hyperpolarization of the cell membrane (3-5). In neurons, the inhibitory action of GlyRs regulate several important physiological functions, like pain transmission, respiratory rhythms, motor coordination, and development (3-7). Like all members of the LGIC superfamily, GlyRs are pentamers composed of five subunits in which each subunit possesses four transmembrane domains arranged to form the ion pore. In this structure, the individual subunits provide extracellular and intracellular domains that play roles in ligand binding and intracellular modulation, respectively (1-3, 5).The function of GlyRs can be effectively modulated by extracellularly acting compounds like strychnine, picrotoxin, zinc ions, and ethanol (3-5, 8, 9). Furthermore, the receptor can also be modulated by intracellular signaling. One of the most studied and recognized pathways involved in regulation of ligandgated ion channel function are phosphorylation processes through protein kinases. Indeed, GlyR and other members of the LGIC superfamily are modulated by activation of cAMPdependent kinases and protein kinase C (10). This involves specific serine residues in the loop between transmembrane domains 3 and 4 (6, 10 -14). On the other hand, recent reports have shown that the activity of GlyRs and nAChRs can be modulated by G protein ␤␥ subunits in a phosphorylation-independent manner (15, 16). In both cases, activation of G proteins, using nonhydrolyzable GTP analogs or by application of purified G␤␥ dimers, generates a strong e...

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Section: Effects Of G Protein Activation On Wild Type and Truncatedsupporting

confidence: 87%

“…Electrophysiology-Whole cell recordings were performed as previously described (16,38). A holding potential of Ϫ60 mV was used.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Effects Of G Protein Activation On Wild Type and Truncatedmentioning

confidence: 99%

mentioning

confidence: 99%

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Molecular Determinants for G Protein βγ Modulation of Ionotropic Glycine Receptors

Yévenes

Moraga-Cid

Guzmán

et al. 2006

Journal of Biological Chemistry

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Receptor Targets in Drug Discovery

Duzic¹,

Marino²,

Williams³

2010

Burger's Medicinal Chemistry and Drug Discovery

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Are nicotinic acetylcholine receptors coupled to G proteins?

et al. 2013

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It was, until recently, accepted that the two classes of acetylcholine (ACh) receptors are distinct in an important sense: muscarinic ACh receptors signal via heterotrimeric GTP binding proteins (G proteins), whereas nicotinic ACh receptors (nAChRs) open to allow flux of Na+, Ca2+, and K+ ions into the cell after activation. Here we present evidence of direct coupling between G proteins and nAChRs in neurons. Based on proteomic, biophysical, and functional evidence, we hypothesize that binding to G proteins modulates the activity and signaling of nAChRs in cells. It is important to note that while this hypothesis is new for the nAChR, it is consistent with known interactions between G proteins and structurally related ligand-gated ion channels. Therefore, it underscores an evolutionarily conserved metabotropic mechanism of G protein signaling via nAChR channels.

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Modulation of glycine-activated ion channel function by G-protein βγ subunits

Cited by 90 publications

References 43 publications

Molecular Determinants for G Protein βγ Modulation of Ionotropic Glycine Receptors

Molecular Determinants for G Protein βγ Modulation of Ionotropic Glycine Receptors

Receptor Targets in Drug Discovery

Are nicotinic acetylcholine receptors coupled to G proteins?

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