scholarly journals Characterization of Heterotrimeric G Protein γ4 Subunit in Rice

2018 ◽  
Vol 19 (11) ◽  
pp. 3596 ◽  
Author(s):  
Sakura Matsuta ◽  
Aki Nishiyama ◽  
Genki Chaya ◽  
Takafumi Itoh ◽  
Kotaro Miura ◽  
...  
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Higher Plants ◽  
Yeast Cells ◽  
Mass Spectrometry Analysis ◽  
Heterotrimeric G Proteins ◽  
Subunit Gene ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
Γ Subunit

Heterotrimeric G proteins are the molecule switch that transmits information from external signals to intracellular target proteins in mammals and yeast cells. In higher plants, heterotrimeric G proteins regulate plant architecture. Rice harbors one canonical α subunit gene (RGA1), four extra-large GTP-binding protein genes (XLGs), one canonical β-subunit gene (RGB1), and five γ-subunit genes (tentatively designated RGG1, RGG2, RGG3/GS3/Mi/OsGGC1, RGG4/DEP1/DN1/qPE9-1/OsGGC3, and RGG5/OsGGC2) as components of the heterotrimeric G protein complex. Among the five γ-subunit genes, RGG1 encodes the canonical γ-subunit, RGG2 encodes a plant-specific type of γ-subunit with additional amino acid residues at the N-terminus, and the remaining three γ-subunit genes encode atypical γ-subunits with cysteine-rich C-termini. We characterized the RGG4/DEP1/DN1/qPE9-1/OsGGC3 gene product Gγ4 in the wild type (WT) and truncated protein Gγ4∆Cys in the RGG4/DEP1/DN1/qPE9-1/OsGGC3 mutant, Dn1-1, as littele information regarding the native Gγ4 and Gγ4∆Cys proteins is currently available. Based on liquid chromatography-tandem mass spectrometry analysis, immunoprecipitated Gγ4 candidates were confirmed as actual Gγ4. Similar to α-(Gα) and β-subunits (Gβ), Gγ4 was enriched in the plasma membrane fraction and accumulated in the developing leaf sheath. As RGG4/DEP1/DN1/qPE9-1/OsGGC3 mutants exhibited dwarfism, tissues that accumulated Gγ4 corresponded to the abnormal tissues observed in RGG4/DEP1/DN1/qPE9-1/OsGGC3 mutants.

scholarly journals Identification of Heterotrimeric G Protein γ3 Subunit in Rice Plasma Membrane

2018 ◽  
Vol 19 (11) ◽  
pp. 3591 ◽  
Author(s):  
Aki Nishiyama ◽  
Sakura Matsuta ◽  
Genki Chaya ◽  
Takafumi Itoh ◽  
Kotaro Miura ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Higher Plants ◽  
Rice Genome ◽  
Amino Acid Residues ◽  
Subunit Gene ◽  
Α Subunit ◽  
Γ Subunit ◽  
Domain Antibody ◽  
C Terminus ◽  
Liquid Chromatography Tandem Mass

Heterotrimeric G proteins are important molecules for regulating plant architecture and transmitting external signals to intracellular target proteins in higher plants and mammals. The rice genome contains one canonical α subunit gene (RGA1), four extra-large GTP-binding protein genes (XLGs), one canonical β subunit gene (RGB1), and five γ subunit genes (tentatively named RGG1, RGG2, RGG3/GS3/Mi/OsGGC1, RGG4/DEP1/DN1/OsGGC3, and RGG5/OsGGC2). RGG1 encodes the canonical γ subunit; RGG2 encodes the plant-specific type of γ subunit with additional amino acid residues at the N-terminus; and the remaining three γ subunit genes encode the atypical γ subunits with cysteine abundance at the C-terminus. We aimed to identify the RGG3/GS3/Mi/OsGGC1 gene product, Gγ3, in rice tissues using the anti-Gγ3 domain antibody. We also analyzed the truncated protein, Gγ3∆Cys, in the RGG3/GS3/Mi/OsGGC1 mutant, Mi, using the anti-Gγ3 domain antibody. Based on nano-liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, the immunoprecipitated Gγ3 candidates were confirmed to be Gγ3. Similar to α (Gα) and β subunits (Gβ), Gγ3 was enriched in the plasma membrane fraction, and accumulated in the flower tissues. As RGG3/GS3/Mi/OsGGC1 mutants show the characteristic phenotype in flowers and consequently in seeds, the tissues that accumulated Gγ3 corresponded to the abnormal tissues observed in RGG3/GS3/Mi/OsGGC1 mutants.

Anesthetics Inhibit Acetylcholine-promoted Guanine Nucleotide Exchange of Heterotrimeric G Proteins of Airway Smooth Muscle

2004 ◽  
Vol 101 (1) ◽  
pp. 120-126 ◽  
Author(s):  
Chie Sakihara ◽  
William J. Perkins ◽  
David O. Warner ◽  
Keith A. Jones
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
G Protein ◽  
Muscarinic Receptor ◽  
G Proteins ◽  
Airway Smooth Muscle ◽  
Smooth Muscle Contraction ◽  
Heterotrimeric G Proteins ◽  
Nucleotide Exchange ◽  
Heterotrimeric G Protein

Background Anesthetics inhibit airway smooth muscle contraction in part by a direct effect on the smooth muscle cell. This study tested the hypothesis that the anesthetics halothane and hexanol, which both relax airway smooth muscle in vitro, inhibit acetylcholine-promoted nucleotide exchange at the alpha subunit of the Gq/11 heterotrimeric G protein (Galphaq/11; i.e., they inhibit muscarinic receptor-Galphaq/11 coupling). Methods The effect of halothane (0.38 +/- 0.02 mm) and hexanol (10 mm) on basal and acetylcholine-stimulated Galphaq/11 guanosine nucleotide exchange was determined in membranes prepared from porcine tracheal smooth muscle. The nonhydrolyzable, radioactive form of guanosine-5'-triphosphate, [S]GTPgammaS, was used as the reporter for Galphaq/11 subunit dissociation from the membrane to soluble fraction, which was immunoprecipitated with rabbit polyclonal anti-Galphaq/11 antiserum. Results Acetylcholine caused a significant time- and concentration-dependent increase in the magnitude of Galphaq/11 nucleotide exchange compared with basal values (i.e., without acetylcholine), reaching a maximal difference at 100 microm (35.9 +/-2.9 vs. 9.8 +/-1.2 fmol/mg protein, respectively). Whereas neither anesthetic had an effect on basal Galphaq/11 nucleotide exchange, both halothane and hexanol significantly inhibited the increase in Galphaq/11 nucleotide exchange produced by 30 microm acetylcholine (by 59% and 68%, respectively). Conclusions Halothane and hexanol interact with the receptor-heterotrimeric G-protein complex in a manner that prevents acetylcholine-promoted exchange of guanosine-5(')-triphosphate for guanosine-5'-diphosphate at Galphaq/11. These data are consistent with the ability of anesthetics to interfere with cellular processes mediated by heterotrimeric G proteins in many cells, including effects on muscarinic receptor-G-protein regulation of airway smooth muscle contraction.

scholarly journals Plant hormone perception and action: a role for G–protein signal transduction?

1998 ◽  
Vol 353 (1374) ◽  
pp. 1425-1430 ◽  
Author(s):  
Richard Hooley
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Plant Hormone ◽  
Higher Plants ◽  
Signalling Pathways ◽  
Heterotrimeric G Proteins ◽  
Extracellular Signals ◽  
G Protein Signalling ◽  
Auxin Signalling

Plants perceive and respond to a profusion of environmental and endogenous signals that influence their growth and development. The G–protein signalling pathway is a mechanism for transducing extracellular signals that is highly conserved in a range of eukaryotes and prokaryotes. Evidence for the existence of G–protein signalling pathways in higher plants is reviewed, and their potential involvement in plant hormone signal transduction evaluated. A range of biochemical and molecular studies have identified potential components of G–protein signalling in plants, most notably a homologue of the G–protein coupled receptor superfamily ( GCR1 ) and the G α and G β subunits of heterotrimeric G–proteins. G–protein agonists and antagonists are known to influence a variety of signalling events in plants and have been used to implicate heterotrimeric G–proteins in gibberellin and possibly auxin signalling. Antisense suppression of GCR1 in Arabidopsis leads to a phenotype which supports a role for this receptor in cytokinin signalling. These observations suggest that higher plants have at least some of the components of G–protein signalling pathways and that these might be involved in the action of certain plant hormones.

scholarly journals Yeast G-proteins mediate directional sensing and polarization behaviors in response to changes in pheromone gradient direction

2013 ◽  
Vol 24 (4) ◽  
pp. 521-534 ◽  
Author(s):  
Travis I. Moore ◽  
Hiromasa Tanaka ◽  
Hyung Joon Kim ◽  
Noo Li Jeon ◽  
Tau-Mu Yi
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Cell Polarity ◽  
Yeast Cells ◽  
Dependent Manner ◽  
Protein Activity ◽  
Gradient Sensing ◽  
Heterotrimeric G Protein ◽  
Low Concentrations ◽  
High Concentrations

Yeast cells polarize by projecting up mating pheromone gradients, a classic cell polarity behavior. However, these chemical gradients may shift direction. We examine how yeast cells sense and respond to a 180o switch in the direction of microfluidically generated pheromone gradients. We identify two behaviors: at low concentrations of α-factor, the initial projection grows by bending, whereas at high concentrations, cells form a second projection toward the new source. Mutations that increase heterotrimeric G-protein activity expand the bending-growth morphology to high concentrations; mutations that increase Cdc42 activity result in second projections at low concentrations. Gradient-sensing projection bending requires interaction between Gβγ and Cdc24, whereas gradient-nonsensing projection extension is stimulated by Bem1 and hyperactivated Cdc42. Of interest, a mutation in Gα affects both bending and extension. Finally, we find a genetic perturbation that exhibits both behaviors. Overexpression of the formin Bni1, a component of the polarisome, makes both bending-growth projections and second projections at low and high α-factor concentrations, suggesting a role for Bni1 downstream of the heterotrimeric G-protein and Cdc42 during gradient sensing and response. Thus we demonstrate that G-proteins modulate in a ligand-dependent manner two fundamental cell-polarity behaviors in response to gradient directional change.

scholarly journals Are prenyl groups on proteins sticky fingers or greasy handles?

2003 ◽  
Vol 376 (1) ◽  
pp. e3-e4 ◽  
Author(s):  
Anthony I. MAGEE ◽  
Miguel C. SEABRA
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
Γ Subunit ◽  
Biochemical Journal

This Commentary discusses the work of Dietrich et al. in this issue of the Biochemical Journal, which sheds new light on the biological roles of protein-bound prenyl groups by providing evidence that the α-subunit of the heterotrimeric G-protein transducin has a binding site for the geranylgeranyl group of the γ-subunit.

scholarly journals Heterotrimeric G protein signaling in polycystic kidney disease

2016 ◽  
Vol 48 (7) ◽  
pp. 429-445 ◽  
Author(s):  
Taketsugu Hama ◽  
Frank Park
Keyword(s):  
Kidney Disease ◽  
G Protein ◽  
Polycystic Kidney Disease ◽  
G Proteins ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Heterotrimeric G Proteins ◽  
Polycystic Kidney ◽  
Heterotrimeric G Protein ◽  
Heterotrimeric G Protein Signaling

Autosomal dominant polycystic kidney disease (ADPKD) is a signalopathy of renal tubular epithelial cells caused by naturally occurring mutations in two distinct genes, polycystic kidney disease 1 ( PKD1) and 2 ( PKD2). Genetic variants in PKD1, which encodes the polycystin-1 (PC-1) protein, remain the predominant factor associated with the pathogenesis of nearly two-thirds of all patients diagnosed with PKD. Although the relationship between defective PC-1 with renal cystic disease initiation and progression remains to be fully elucidated, there are numerous clinical studies that have focused upon the control of effector systems involving heterotrimeric G protein regulation. A major regulator in the activation state of heterotrimeric G proteins are G protein-coupled receptors (GPCRs), which are defined by their seven transmembrane-spanning regions. PC-1 has been considered to function as an unconventional GPCR, but the mechanisms by which PC-1 controls signal processing, magnitude, or trafficking through heterotrimeric G proteins remains to be fully known. The diversity of heterotrimeric G protein signaling in PKD is further complicated by the presence of non-GPCR proteins in the membrane or cytoplasm that also modulate the functional state of heterotrimeric G proteins within the cell. Moreover, PC-1 abnormalities promote changes in hormonal systems that ultimately interact with distinct GPCRs in the kidney to potentially amplify or antagonize signaling output from PC-1. This review will focus upon the canonical and noncanonical signaling pathways that have been described in PKD with specific emphasis on which heterotrimeric G proteins are involved in the pathological reorganization of the tubular epithelial cell architecture to exacerbate renal cystogenic pathways.

Heterotrimeric G proteins in heart disease

2000 ◽  
Vol 78 (3) ◽  
pp. 187-198 ◽  
Author(s):  
Oliver Zolk ◽  
Ichiro Kouchi ◽  
Petra Schnabel ◽  
Michael Böhm
Keyword(s):  
Heart Failure ◽  
G Protein ◽  
G Proteins ◽  
Binding Proteins ◽  
Molecular Mechanisms ◽  
Heart Diseases ◽  
Membrane Receptors ◽  
Adrenergic System ◽  
Heterotrimeric G Proteins ◽  
Heterotrimeric G Protein

Guanine nucleotide binding proteins (G proteins) are largely grouped into three classes: heterotrimeric G proteins, ras-like or small molecular weight GTP binding proteins, and others like Gh. In the heart G proteins transduce signals from a variety of membrane receptors to generate diverse effects on contractility, heart rate, and myocyte growth. This central position of G proteins forming a switchboard between extracellular signals and intracellular effectors makes them candidates possibly involved in the pathogenesis of cardiac hypertrophy, heart failure, and arrhythmia. This review focuses primarily on discoveries of heterotrimeric G protein alterations in heart diseases that help us to understand the pathogenesis and pathophysiology. We also discuss the underlying molecular mechanisms of heterotrimeric G protein signalling.Key words: G proteins, signal transduction, adrenergic system, heart failure, hypertrophy.

Heterotrimeric G protein Giis involved in a signal transduction pathway for ATP release from erythrocytes

2004 ◽  
Vol 286 (3) ◽  
pp. H940-H945 ◽  
Author(s):  
Jeffrey J. Olearczyk ◽  
Alan H. Stephenson ◽  
Andrew J. Lonigro ◽  
Randy S. Sprague
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Atp Release ◽  
Signal Transduction Pathway ◽  
Protein G ◽  
Transduction Pathway ◽  
Heterotrimeric G Proteins ◽  
Heterotrimeric G Protein

Erythrocytes are reported to release ATP in response to mechanical deformation and decreased oxygen tension. Previously we proposed that receptor-mediated activation of the heterotrimeric G protein Gsresulted in ATP release from erythrocytes. Here we investigate the hypothesis that activation of heterotrimeric G proteins of the Gisubtype are also involved in a signal transduction pathway for ATP release from rabbit erythrocytes. Heterotrimeric G proteins Gαi1, Gαi2, and Gαi3but not Gαowere identified in rabbit and human erythrocyte membranes. Pretreatment of rabbit erythrocytes with pertussis toxin (100 ng/ml, 2 h), which uncouples Gi/ofrom their effector proteins, inhibited deformation-induced ATP release. Incubation of rabbit and human erythrocytes with mastoparan (Mas, 10 μM) or Mas-7 (1 μM), which are compounds that directly activate Giproteins, resulted in ATP release. However, rabbit erythrocytes did not release ATP when incubated with Mas-17 (10 μM), which is an inactive Mas analog. In separate experiments, Mas (10 μM) but not Mas-17 (10 μM) increased intracellular concentrations of cAMP when incubated with rabbit erythrocytes. Importantly, Mas-induced ATP release from rabbit erythrocytes was inhibited after treatment with pertussis toxin (100 ng/ml, 2 h). These data are consistent with the hypothesis that the heterotrimeric G protein Giis a component of a signal transduction pathway for ATP release from erythrocytes.

scholarly journals Heterotrimeric G proteins promote FLS2 protein accumulation through inhibition of FLS2 autophagic degradation

2018 ◽  
Author(s):  
Jimi C. Miller ◽  
Stacey A. Lawrence ◽  
Nicole K. Clay
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
G Proteins ◽  
Protein Complex ◽  
Heterotrimeric G Proteins ◽  
Immune Signaling ◽  
Heterotrimeric G Protein ◽  
Protein Levels ◽  
Autophagic Degradation ◽  
Protein Components

ABSTRACTFLAGELLIN-SENSITIVE 2 (FLS2) is a plant immune receptor that binds bacterial flagellin to activate immune signaling. This immune signal is transduced by a heterotrimeric G protein complex at the plasma membrane and activates downstream signaling. However, it is unknown whether the heterotrimeric G proteins have functions at other subcellular locations away from the plasma membrane. Here, we show that components of the heterotrimeric G protein complex stabilize FLS2 protein levels by inhibiting the autophagic degradation of FLS2. Using genetic analysis, we determined that mutations of G protein components resulted in reduced immune signaling in part due to decreased FLS2 protein levels. Furthermore, reduction of FLS2 protein levels was caused by elevated proteasomal and autophagic degradation of FLS2. Genetic inhibition of autophagy in G protein mutants rescued FLS2 levels and immunity. Our findings suggest that the heterotrimeric G protein components, in addition to being part of the heterotrimeric G protein complex that transduces signals at the plasma membrane, also function away from the plasma membrane to control FLS2 protein levels. These results expand the functional capacity of the heterotrimeric G protein complexes in plant immunity.

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