scholarly journals Regulation of bifunctional proteins in cells: Lessons from the phospholipase Cβ/G protein pathway

2019 ◽  
Vol 29 (6) ◽  
pp. 1258-1268
Author(s):  
Lela Jackson ◽  
Androniqi Qifti ◽  
Katherine M. Pearce ◽  
Suzanne Scarlata
Keyword(s):  
G Protein ◽  
Bifunctional Proteins ◽  
In Cells

scholarly journals ER/K linked GPCR-G protein fusions systematically modulate second messenger response in cells

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Rabia U. Malik ◽  
Matthew Dysthe ◽  
Michael Ritt ◽  
Roger K. Sunahara ◽  
Sivaraj Sivaramakrishnan
Keyword(s):  
G Protein ◽  
Second Messenger ◽  
In Cells

Development and validation of algorithms for measuring G-protein coupled receptor activation in cells using the LSC-based imaging cytometer platform

2005 ◽  
Vol 65A (1) ◽  
pp. 69-76 ◽  
Author(s):  
Kazuo Ozawa ◽  
Christine C. Hudson ◽  
Kirsten R. Wille ◽  
Sachiko Karaki ◽  
Robert H. Oakley
Keyword(s):  
G Protein ◽  
Receptor Activation ◽  
G Protein Coupled Receptor ◽  
Development And Validation ◽  
G Protein Coupled ◽  
In Cells

Activation of ERK and JNK by urea depends on small G-protein of the RHO family only in cells preadapted to urea: A link to apoptosis?

1999 ◽  
Vol 91 (7) ◽  
pp. 559-559
Author(s):  
Dominique Guivarc'h ◽  
Stéphanie Michelet ◽  
Céline Badier ◽  
Chantal Colmont ◽  
Pierre Ripoche ◽  
...  
Keyword(s):  
G Protein ◽  
Small G Protein ◽  
Rho Family ◽  
In Cells

scholarly journals Dopamine-D2S Receptor Inhibition of Calcium Influx, Adenylyl Cyclase, and Mitogen-Activated Protein Kinase in Pituitary Cells: Distinct Gα and Gβγ Requirements

2002 ◽  
Vol 16 (10) ◽  
pp. 2393-2404 ◽  
Author(s):  
Behzad Banihashemi ◽  
Paul R. Albert
Keyword(s):  
Adenylyl Cyclase ◽  
G Protein ◽  
Calcium Influx ◽  
Short Form ◽  
Mitogen Activated Protein Kinase ◽  
Pituitary Cells ◽  
Protein Receptor ◽  
Dependent Inhibition ◽  
Erk Kinase ◽  
In Cells

Abstract The G protein specificity of multiple signaling pathways of the dopamine-D2S (short form) receptor was investigated in GH4ZR7 lactotroph cells. Activation of the dopamine-D2S receptor inhibited forskolin-induced cAMP production, reduced BayK8644- activated calcium influx, and blocked TRH-mediated p42/p44 MAPK phosphorylation. These actions were blocked by pretreatment with pertussis toxin (PTX), indicating mediation by Gi/o proteins. D2S stimulation also decreased TRH-induced MAPK/ERK kinase phosphorylation. TRH induced c-Raf but not B-Raf activation, and the D2S receptor inhibited both TRH-induced c-Raf and basal B-Raf kinase activity. After PTX treatment, D2S receptor signaling was rescued in cells stably transfected with individual PTX-insensitive Gα mutants. Inhibition of adenylyl cyclase was partly rescued by Gαi2 or Gαi3, but Gαo alone completely reconstituted D2S-mediated inhibition of BayK8644-induced L-type calcium channel activation. Gαo and Gαi3 were the main components involved in D2S-mediated p42/44 MAPK inhibition. In cells transfected with the carboxyl-terminal domain of G protein receptor kinase to inhibit Gβγ signaling, only D2S-mediated inhibition of calcium influx was blocked, but not inhibition of adenylyl cyclase or MAPK. These results indicate that the dopamine-D2S receptor couples to distinct Gi/o proteins, depending on the pathway addressed, and suggest a novel Gαi3/Gαo-dependent inhibition of MAPK mediated by c-Raf and B-Raf-dependent inhibition of MAPK/ERK kinase.

scholarly journals Regulators of G Protein Signaling Attenuate the G Protein–mediated Inhibition of N-Type Ca Channels

1999 ◽  
Vol 113 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Karim Melliti ◽  
Ulises Meza ◽  
Rory Fisher ◽  
Brett Adams
Keyword(s):  
G Protein ◽  
G Proteins ◽  
G Protein Signaling ◽  
Rgs Proteins ◽  
Ca Channel ◽  
Protein Signaling ◽  
Ca Channels ◽  
Channel Inhibition ◽  
Kinetics Of ◽  
In Cells

Regulators of G protein signaling (RGS) proteins bind to the α subunits of certain heterotrimeric G proteins and greatly enhance their rate of GTP hydrolysis, thereby determining the time course of interactions among Gα, Gβγ, and their effectors. Voltage-gated N-type Ca channels mediate neurosecretion, and these Ca channels are powerfully inhibited by G proteins. To determine whether RGS proteins could influence Ca channel function, we recorded the activity of N-type Ca channels coexpressed in human embryonic kidney (HEK293) cells with G protein–coupled muscarinic (m2) receptors and various RGS proteins. Coexpression of full-length RGS3T, RGS3, or RGS8 significantly attenuated the magnitude of receptor-mediated Ca channel inhibition. In control cells expressing α1B, α2, and β3 Ca channel subunits and m2 receptors, carbachol (1 μM) inhibited whole-cell currents by ∼80% compared with only ∼55% inhibition in cells also expressing exogenous RGS protein. A similar effect was produced by expression of the conserved core domain of RGS8. The attenuation of Ca current inhibition resulted primarily from a shift in the steady state dose–response relationship to higher agonist concentrations, with the EC50 for carbachol inhibition being ∼18 nM in control cells vs. ∼150 nM in RGS-expressing cells. The kinetics of Ca channel inhibition were also modified by RGS. Thus, in cells expressing RGS3T, the decay of prepulse facilitation was slower, and recovery of Ca channels from inhibition after agonist removal was faster than in control cells. The effects of RGS proteins on Ca channel modulation can be explained by their ability to act as GTPase-accelerating proteins for some Gα subunits. These results suggest that RGS proteins may play important roles in shaping the magnitude and kinetics of physiological events, such as neurosecretion, that involve G protein–modulated Ca channels.

scholarly journals Complementary biosensors reveal different G-protein signaling modes triggered by GPCRs and non-receptor activators

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Mikel Garcia-Marcos
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein Signaling ◽  
Heterotrimeric G Proteins ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Cytoplasmic Proteins ◽  
Nucleotide Exchange Factor ◽  
In Cells

It has become evident that activation of heterotrimeric G-proteins by cytoplasmic proteins that are not G-protein-coupled receptors (GPCRs) plays a role in physiology and disease. Despite sharing the same biochemical guanine nucleotide exchange factor (GEF) activity as GPCRs in vitro, the mechanisms by which these cytoplasmic proteins trigger G-protein-dependent signaling in cells have not been elucidated. Heterotrimeric G-proteins can give rise to two active signaling species, Gα-GTP and dissociated Gβγ, with different downstream effectors, but how non-receptor GEFs affect the levels of these two species in cells is not known. Here, a systematic comparison of GPCRs and three unrelated non-receptor proteins with GEF activity in vitro (GIV/Girdin, AGS1/Dexras1, and Ric-8A) revealed high divergence in their contribution to generating Gα-GTP and free Gβγ in cells directly measured with live-cell biosensors. These findings demonstrate fundamental differences in how receptor and non-receptor G-protein activators promote signaling in cells despite sharing similar biochemical activities in vitro.

scholarly journals Localization and Signaling of GβSubunit Ste4p Are Controlled by a-Factor Receptor and thea-Specific Protein Asg7p

2000 ◽  
Vol 20 (23) ◽  
pp. 8826-8835 ◽  
Author(s):  
Jinah Kim ◽  
Eric Bortz ◽  
Hualin Zhong ◽  
Thomas Leeuw ◽  
Ekkehard Leberer ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Subcellular Location ◽  
Regulatory Process ◽  
Yeast Cells ◽  
Specific Gene ◽  
Β Subunit ◽  
Pheromone Signaling ◽  
Receptor Inhibition ◽  
In Cells

ABSTRACT Haploid yeast cells initiate pheromone signaling upon the binding of pheromone to its receptor and activation of the coupled G protein. A regulatory process termed receptor inhibition blocks pheromone signaling when the a-factor receptor is inappropriately expressed inMATa cells. Receptor inhibition blocks signaling by inhibiting the activity of the G protein β subunit, Ste4p. To investigate how Ste4p activity is inhibited, its subcellular location was examined. In wild-type cells, α-factor treatment resulted in localization of Ste4p to the plasma membrane of mating projections. In cells expressing the a-factor receptor, α-factor treatment resulted in localization of Ste4p away from the plasma membrane to an internal compartment. An altered version of Ste4p that is largely insensitive to receptor inhibition retained its association with the membrane in cells expressing the a-factor receptor. The inhibitory function of the a-factor receptor required ASG7, an a-specific gene of previously unknown function. ASG7 RNA was induced by pheromone, consistent with increased inhibition as the pheromone response progresses. The a-factor receptor inhibited signaling in its liganded state, demonstrating that the receptor can block the signal that it initiates. ASG7 was required for the altered localization of Ste4p that occurs during receptor inhibition, and the subcellular location of Asg7p was consistent with its having a direct effect on Ste4p localization. These results demonstrate that Asg7p mediates a regulatory process that blocks signaling from a G protein β subunit and causes its relocalization within the cell.

scholarly journals Effect of microtubule assembly status on the intracellular processing and surface expression of an integral protein of the plasma membrane.

1984 ◽  
Vol 99 (3) ◽  
pp. 1101-1109 ◽  
Author(s):  
A A Rogalski ◽  
J E Bergmann ◽  
S J Singer
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
G Protein ◽  
Rough Endoplasmic Reticulum ◽  
Intracellular Transport ◽  
Temperature Shift ◽  
Surface Expression ◽  
Microtubule Assembly ◽  
In Cells

We studied the effects of changes in microtubule assembly status upon the intracellular transport of an integral membrane protein from the rough endoplasmic reticulum to the plasma membrane. The protein was the G glycoprotein of vesicular stomatitis virus in cells infected with the Orsay-45 temperature-sensitive mutant of the virus; the synchronous intracellular transport of the G protein could be initiated by a temperature shift-down protocol. The intracellular and surface-expressed G protein were separately detected and localized in the same cells at different times after the temperature shift, by double-immunofluorescence microscopic measurements, and the extent of sialylation of the G protein at different times was quantitated by immunoprecipitation and SDS PAGE of [35S]methionine-labeled cell extracts. Neither complete disassembly of the cytoplasmic microtubules by nocodazole treatment, nor the radical reorganization of microtubules upon taxol treatment, led to any perceptible changes in the rate or extent of G protein sialylation, nor to any marked changes in the rate or extent of surface appearance of the G protein. However, whereas in control cells the surface expression of G was polarized, at membrane regions in juxtaposition to the perinuclear compact Golgi apparatus, in cells with disassembled microtubules the surface expression of the G protein was uniform, corresponding to the intracellular dispersal of the elements of the Golgi apparatus. The mechanisms of transfer of integral proteins from the rough endoplasmic reticulum to the Golgi apparatus, and from the Golgi apparatus to the plasma membrane, are discussed in the light of these observations, and compared with earlier studies of the intracellular transport of secretory proteins.

scholarly journals Decreased expression of a member of the Rho GTPase family, Cdc42Hs, in cells from Tangier disease - the small G protein may play a role in cholesterol efflux

FEBS Letters ◽  
2000 ◽  
Vol 484 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Ken-ichi Hirano ◽  
Fumihiko Matsuura ◽  
Kosuke Tsukamoto ◽  
Zhongyan Zhang ◽  
Akifumi Matsuyama ◽  
...  
Keyword(s):  
G Protein ◽  
Cholesterol Efflux ◽  
Rho Gtpase ◽  
Tangier Disease ◽  
Small G Protein ◽  
In Cells
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