Identification of two α-subunit species of GTP-binding proteins, Gα15 and Gαq, expressed in rat taste buds

Kusakabe, Yuko; Yamaguchi, Eiri; Tanemura, Kentaro; Kameyama, Kimihiko; Chiba, Noboru; Arai, Soichi; Emori, Yasufumi; Abe, Keiko

doi:10.1016/s0167-4889(98)00062-7

Cited by 46 publications

(26 citation statements)

References 35 publications

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“…At these higher concentrations of tastants, the G352P-␣-gustducin protein acted as a dominant negative to inhibit the gustducin-independent mechanisms operating in ␣-gustducin-null mice. These results suggest that these ''backup'' mechanisms use another G-protein ␣-subunit expressed in the same TRCs that normally express gustducin; possible candidates include ␣-transducin, ␣ i2 , ␣ i3 , ␣ 14 , ␣ 15 , or ␣ S , which have been shown to be present in TRCs (1,(31)(32)(33).…”

Section: Resultsmentioning

confidence: 93%

Dominant loss of responsiveness to sweet and bitter compounds caused by a single mutation in α-gustducin

Ruiz-Avila

Wong

Damak

et al. 2001

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

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Biochemical and genetic studies have implicated ␣-gustducin as a key component in the transduction of both bitter or sweet taste. Yet, ␣-gustducin-null mice are not completely unresponsive to bitter or sweet compounds. To gain insights into how gustducin mediates responses to bitter and sweet compounds, and to elicit the nature of the gustducin-independent pathways, we generated a dominant-negative form of ␣-gustducin and expressed it as a transgene from the ␣-gustducin promoter in both wild-type and ␣-gustducin-null mice. A single mutation, G352P, introduced into the C-terminal region of ␣-gustducin critical for receptor interaction rendered the mutant protein unresponsive to activation by taste receptor, but left its other functions intact. In control experiments, expression of wild-type ␣-gustducin as a transgene in ␣-gustducin-null mice fully restored responsiveness to bitter and sweet compounds, formally proving that the targeted deletion of the ␣-gustducin gene caused the taste deficits of the null mice. In contrast, transgenic expression of the G352P mutant did not restore responsiveness of the null mice to either bitter or sweet compounds. Furthermore, in the wild-type background, the mutant transgene inhibited endogenous ␣-gustducin's interactions with taste receptors, i.e., it acted as a dominant-negative. That the mutant transgene further diminished the residual bitter and sweet taste responsiveness of the ␣-gustducin-null mice suggests that other guanine nucleotide-binding regulatory proteins expressed in the ␣-gustducin lineage of taste cells mediate these responses.

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Section: Resultsmentioning

confidence: 93%

Dominant loss of responsiveness to sweet and bitter compounds caused by a single mutation in α-gustducin

Ruiz-Avila

Wong

Damak

et al. 2001

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

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“…1). Furthermore, northern blot analysis detected Ga15 mRNA in rat tongue epithelia (Kusakabe et al 1998).…”

Section: Epitheliamentioning

confidence: 99%

The puzzling uniqueness of the heterotrimeric G15 protein and its potential beyond hematopoiesis

Giannone¹,

Malpeli

Lisi

et al. 2010

Journal of Molecular Endocrinology

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Heterotrimeric G proteins transduce the signals of the largest family of membrane receptors (G protein-coupled receptors, GPCRs) hence triggering the activation of a wide variety of physiological responses. G15 is a G protein characterized by a number of functional peculiarities that make its signaling exceptional: 1) it can couple a variety of Gs-, Gi/o-, and Gq-linked receptors to phospholipase C activation; 2) relatively to other G proteins, it is poorly affected by b-arrestin-dependent desensitization, the general mechanism that regulates GPCR function and 3) at the protein level, its expression is only detected in highly specific cell types (hematopoietic and epithelial cells). G15 a-subunit displays unique structural and biochemical properties, and is phylogenetically the most recent and divergent component of the Gaq/11 subfamily. All these aspects shed a mysterious light on G15 biological role, which remains substantially elusive. Thus, far, G15 signaling has been analyzed in the context of hematopoiesis. Here, we highlight observations supporting the view that G15 functions may extend further beyond the immune system. In addition, we describe puzzling aspects of G15 signaling that offer a novel perspective in the understanding of its physiological role.

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“…G␣ i-2 , G␣ i-3 , G␣ 14 , G␣ 15 , G␣ q , G␣ s , and ␣-transducin (7,11,18)). One or more of these G protein ␣-subunits may play a role in bitter taste transduction because ␣-gustducin knockout mice retain residual responsiveness to * This minireview will be reprinted in the 2002 Minireview Compendium, which will be available in December, 2002.…”

Section: Bitter Transductionmentioning

confidence: 99%

Molecular Mechanisms of Bitter and Sweet Taste Transduction

Margolskee

2002

Journal of Biological Chemistry

388

271

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Identification of two α-subunit species of GTP-binding proteins, Gα15 and Gαq, expressed in rat taste buds

Cited by 46 publications

References 35 publications

Dominant loss of responsiveness to sweet and bitter compounds caused by a single mutation in α-gustducin

Dominant loss of responsiveness to sweet and bitter compounds caused by a single mutation in α-gustducin

The puzzling uniqueness of the heterotrimeric G15 protein and its potential beyond hematopoiesis

Molecular Mechanisms of Bitter and Sweet Taste Transduction

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