Do Plants Contain G Protein-Coupled Receptors?

Taddese, Bruck; Upton, Graham; Bailey, Gregory R.; Jordan, Siân R.D.; Abdulla, Nuradin Y.; Reeves, Philip J.; Reynolds, Christopher A.

doi:10.1104/pp.113.228874

Cited by 62 publications

(62 citation statements)

References 121 publications

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“…While competition between GPA1 and XLGs for Gbg could be a common theme, it is also possible that XLG-and GPA1-based heterotrimers modulate shared molecular signaling pathways. GPA1 interacts with GCR1, the only putative Arabidopsis G protein-coupled receptor based on sequence and structural homology (Plakidou-Dymock et al, 1998;Pandey and Assmann, 2004;Warpeha et al, 2007;Taddese et al, 2014), GTG1/GTG2, the two Arabidopsis G protein-coupled receptor-type G proteins (Pandey et al, 2009), and RGS1, the sole demonstrated Ga GTPase-activating protein in Arabidopsis . The potential interactions of the XLGs with these signaling elements remain to be explored.…”

Section: Xlgs As Noncanonical Ga Proteinsmentioning

confidence: 99%

Extra-Large G Proteins Expand the Repertoire of Subunits in Arabidopsis Heterotrimeric G Protein Signaling

et al. 2015

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Heterotrimeric G proteins, consisting of Ga, Gb, and Gg subunits, are a conserved signal transduction mechanism in eukaryotes. However, G protein subunit numbers in diploid plant genomes are greatly reduced as compared with animals and do not correlate with the diversity of functions and phenotypes in which heterotrimeric G proteins have been implicated. In addition to GPA1, the sole canonical Arabidopsis (Arabidopsis thaliana) Ga subunit, Arabidopsis has three related proteins: the extra-large GTP-binding proteins XLG1, XLG2, and XLG3. We demonstrate that the XLGs can bind Gbg dimers (AGB1 plus a Gg subunit: AGG1, AGG2, or AGG3) with differing specificity in yeast (Saccharomyces cerevisiae) three-hybrid assays. Our in silico structural analysis shows that XLG3 aligns closely to the crystal structure of GPA1, and XLG3 also competes with GPA1 for Gbg binding in yeast. We observed interaction of the XLGs with all three Gbg dimers at the plasma membrane in planta by bimolecular fluorescence complementation. Bioinformatic and localization studies identified and confirmed nuclear localization signals in XLG2 and XLG3 and a nuclear export signal in XLG3, which may facilitate intracellular shuttling. We found that tunicamycin, salt, and glucose hypersensitivity and increased stomatal density are agb1-specific phenotypes that are not observed in gpa1 mutants but are recapitulated in xlg mutants. Thus, XLG-Gbg heterotrimers provide additional signaling modalities for tuning plant G protein responses and increase the repertoire of G protein heterotrimer combinations from three to 12. The potential for signal partitioning and competition between the XLGs and GPA1 is a new paradigm for plant-specific cell signaling.

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Section: Xlgs As Noncanonical Ga Proteinsmentioning

confidence: 99%

Extra-Large G Proteins Expand the Repertoire of Subunits in Arabidopsis Heterotrimeric G Protein Signaling

et al. 2015

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“…Instead, the Gα subunit of the heterotrimeric G protein complex is typically already bound to GTP, with regulation of activity at the level of GTP hydrolysis to halt signaling (Urano and Jones, 2014). Of the 56 putative plant GPCRs identified based on structural homology, only a single candidate -GCR1 -has features consistent with it functioning as a bona fide GPCR with GEF activity (Taddese et al, 2014). Whether or not GCR1 acts as a GEF remains to be determined.…”

Section: Introductionmentioning

confidence: 99%

Outside-in signaling – a brief review of GPCR signaling with a focus on the Drosophila GPCR family

Hanlon

Andrew

2015

Journal of Cell Science

111

120

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G-protein-coupled receptors (GPCRs) are the largest family of receptors in many organisms, including worms, mice and humans. GPCRs are seven-transmembrane pass proteins that are activated by binding a stimulus (or ligand) in the extracellular space and then transduce that information to the inside of the cell through conformational changes. The conformational changes activate heterotrimeric G-proteins, which execute the downstream signaling pathways through the recruitment and activation of cellular enzymes. The highly specific ligand-GPCR interaction prompts an efficient cellular response, which is vital for the health of the cell and organism. In this Commentary, we review general features of GPCR signaling and then focus on the Drosophila GPCRs, which are not as wellcharacterized as their worm and mammalian counterparts. We discuss findings that the Drosophila odorant and gustatory receptors are not bona fide GPCRs as is the case for their mammalian counterparts. We also present here a phylogenetic analysis of the bona fide Drosophila GPCRs that suggest potential roles for several family members. Finally, we discuss recently discovered roles of GPCRs in Drosophila embryogenesis, a field we expect will uncover many previously unappreciated functions for GPCRs.

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“…This localization contrasts with that of the Drosophila and mouse GPHRs, which were found at intracellular membranes (4,5). Recently, the view that GTG1 and GTG2 have a GPCR-type structure has been challenged, since they have more than seven predicted transmembrane regions (6).…”

mentioning

confidence: 70%

The Dictyostelium discoideum GPHR Ortholog Is an Endoplasmic Reticulum and Golgi Protein with Roles during Development

et al. 2015

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Dictyostelium discoideum GPHR (Golgi pH regulator)/Gpr89 is a developmentally regulated transmembrane protein present on the endoplasmic reticulum (ER) and the Golgi apparatus. Transcript levels are low during growth and vary during development, reaching high levels during the aggregation and late developmental stages. The Arabidopsis ortholog was described as a G protein-coupled receptor (GPCR) for abscisic acid present at the plasma membrane, whereas the mammalian ortholog is a Golgi apparatus-associated anion channel functioning as a Golgi apparatus pH regulator. To probe its role in D. discoideum, we generated a strain lacking GPHR. The mutant had different growth characteristics than the AX2 parent strain, exhibited changes during late development, and formed abnormally shaped small slugs and fruiting bodies. An analysis of development-specific markers revealed that their expression was disturbed. The distributions of the endoplasmic reticulum and the Golgi apparatus were unaltered at the immunofluorescence level. Likewise, their functions did not appear to be impaired, since membrane proteins were properly processed and glycosylated. Also, changes in the external pH were sensed by the ER, as indicated by a pH-sensitive ER probe, as in the wild type.

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Do Plants Contain G Protein-Coupled Receptors?

Cited by 62 publications

References 121 publications

Extra-Large G Proteins Expand the Repertoire of Subunits in Arabidopsis Heterotrimeric G Protein Signaling

Extra-Large G Proteins Expand the Repertoire of Subunits in Arabidopsis Heterotrimeric G Protein Signaling

Outside-in signaling – a brief review of GPCR signaling with a focus on the Drosophila GPCR family

The Dictyostelium discoideum GPHR Ortholog Is an Endoplasmic Reticulum and Golgi Protein with Roles during Development

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