scholarly journals Vesicular Transport Is Not Required for the Cytoplasmic Pool of Cholera Toxin To Interact with the Stimulatory Alpha Subunit of the Heterotrimeric G Protein

2004 ◽  
Vol 72 (12) ◽  
pp. 6826-6835 ◽  
Author(s):  
Ken Teter ◽  
Michael G. Jobling ◽  
Randall K. Holmes
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Cholera Toxin ◽  
G Protein ◽  
Vesicular Transport ◽  
Cytotoxic Action ◽  
Anterograde Transport ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
Vesicular Traffic

ABSTRACT Cholera toxin (CT) moves from the cell surface to the endoplasmic reticulum (ER) by retrograde vesicular transport. The catalytic A1 polypeptide of CT (CTA1) then crosses the ER membrane, enters the cytosol, ADP-ribosylates the stimulatory α subunit of the heterotrimeric G protein (Gsα) at the cytoplasmic face of the plasma membrane, and activates adenylate cyclase. The cytosolic pool of CTA1 may reach the plasma membrane and its Gsα target by traveling on anterograde-directed transport vesicles. We examined this possibility with the use of a plasmid-based transfection system that directed newly synthesized CTA1 to either the ER lumen or the cytosol of CHO cells. Such a system allowed us to bypass the CT retrograde trafficking itinerary from the cell surface to the ER. Previous work has shown that the ER-localized pool of CTA1 is rapidly exported from the ER to the cytosol. Expression of CTA1 in either the ER or the cytosol led to the activation of Gsα, and Gsα activation was not inhibited in transfected cells exposed to drugs that inhibit vesicular traffic. Thus, anterograde transport from the ER to the plasma membrane is not required for the cytotoxic action of CTA1.

scholarly journals Activation of a plant plasma membrane Ca2+channel by TGα1, a heterotrimeric G protein α-subunit homologue

FEBS Letters ◽  
1998 ◽  
Vol 424 (1-2) ◽  
pp. 17-21 ◽  
Author(s):  
Gilad S Aharon ◽  
Angie Gelli ◽  
Wayne A Snedden ◽  
Eduardo Blumwald
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
G Protein Α Subunit ◽  
Plant Plasma Membrane

scholarly journals Heterotrimeric G-Protein Alpha (α) Subunit from a. Thaliana Forms Trimeric Structures in Solution

2016 ◽  
Vol 110 (3) ◽  
pp. 380a
Author(s):  
Ersoy Cholak ◽  
Ines Karmous ◽  
Bihter Avşar ◽  
Zehra Sayers
Keyword(s):  
G Protein ◽  
Heterotrimeric G Protein ◽  
Α Subunit

scholarly journals Activation of Protein Kinase D by Signaling through the α Subunit of the Heterotrimeric G Protein Gq

2000 ◽  
Vol 275 (3) ◽  
pp. 2157-2164 ◽  
Author(s):  
Jingzhen Yuan ◽  
Lee Slice ◽  
John H. Walsh ◽  
Enrique Rozengurt
Keyword(s):  
Protein Kinase ◽  
G Protein ◽  
Protein Kinase D ◽  
Heterotrimeric G Protein ◽  
Α Subunit

scholarly journals Rational design of a heterotrimeric G protein α subunit with artificial inhibitor sensitivity

2019 ◽  
Vol 294 (15) ◽  
pp. 5747-5758 ◽  
Author(s):  
Davide Malfacini ◽  
Julian Patt ◽  
Suvi Annala ◽  
Kasper Harpsøe ◽  
Funda Eryilmaz ◽  
...  
Keyword(s):  
G Protein ◽  
Rational Design ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
G Protein Α Subunit

The Receptor-Bound “Empty Pocket” State of the Heterotrimeric G-Protein α-Subunit Is Conformationally Dynamic†

Biochemistry ◽  
2006 ◽  
Vol 45 (43) ◽  
pp. 12986-12997 ◽  
Author(s):  
Najmoutin G. Abdulaev ◽  
Tony Ngo ◽  
Eva Ramon ◽  
Danielle M. Brabazon ◽  
John P. Marino ◽  
...  
Keyword(s):  
G Protein ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
G Protein Α Subunit

scholarly journals Estradiol activates epithelial sodium channels in rat alveolar cells through the G protein-coupled estrogen receptor

2013 ◽  
Vol 305 (11) ◽  
pp. L878-L889 ◽  
Author(s):  
Megan M. Greenlee ◽  
Jeremiah D. Mitzelfelt ◽  
Ling Yu ◽  
Qiang Yue ◽  
Billie Jeanne Duke ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Plasma Membrane ◽  
G Protein ◽  
Sodium Channels ◽  
Female Rats ◽  
Channel Activity ◽  
Alveolar Cells ◽  
Α Subunit ◽  
Female Sex ◽  
G Protein Coupled

Female sex predisposes individuals to poorer outcomes during respiratory disorders like cystic fibrosis and influenza-associated pneumonia. A common link between these disorders is dysregulation of alveolar fluid clearance via disruption of epithelial sodium channel (ENaC) activity. Recent evidence suggests that female sex hormones directly regulate expression and activity of alveolar ENaC. In our study, we identified the mechanism by which estradiol (E2) or progesterone (P4) independently regulates alveolar ENaC. Using cell-attached patch clamp, we measured ENaC single-channel activity in a rat alveolar cell line (L2) in response to overnight exposure to either E2 or P4. In contrast to P4, E2 increased ENaC channel activity ( NPo) through an increase in channel open probability ( Po) and an increased number of patches with observable channel activity. Apical plasma membrane abundance of the ENaC α-subunit (αENaC) more than doubled in response to E2 as determined by cell surface biotinylation. αENaC membrane abundance was approximately threefold greater in lungs from female rats in proestrus, when serum E2 is greatest, compared with diestrus, when it is lowest. Our results also revealed a significant role for the G protein-coupled estrogen receptor (Gper) to mediate E2's effects on ENaC. Overall, our results demonstrate that E2 signaling through Gper selectively activates alveolar ENaC through an effect on channel gating and channel density, the latter via greater trafficking of channels to the plasma membrane. The results presented herein implicate E2-mediated regulation of alveolar sodium channels in the sex differences observed in the pathogenesis of several pulmonary diseases.

scholarly journals Study of novel d1 alleles, defective mutants of the α subunit of heterotrimeric G-protein in rice

2009 ◽  
Vol 84 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Katsuyuki Oki ◽  
Noriko Inaba ◽  
Hidemi Kitano ◽  
Sachiko Takahashi ◽  
Yukiko Fujisawa ◽  
...  
Keyword(s):  
G Protein ◽  
Heterotrimeric G Protein ◽  
Α Subunit

scholarly journals Heterotrimeric G protein α subunit is involved in rice brassinosteroid response

Cell Research ◽  
2006 ◽  
Vol 16 (12) ◽  
pp. 916-922 ◽  
Author(s):  
Lei Wang ◽  
Yun-Yuan Xu ◽  
Qi-Bin Ma ◽  
Dan Li ◽  
Zhi-Hong Xu ◽  
...  
Keyword(s):  
G Protein ◽  
Heterotrimeric G Protein ◽  
Α Subunit ◽  
G Protein Α Subunit

scholarly journals Dynamic Regulation of a GPCR-Tetraspanin-G Protein Complex on Intact Cells: Central Role of CD81 in Facilitating GPR56-Gαq/11Association

2004 ◽  
Vol 15 (5) ◽  
pp. 2375-2387 ◽  
Author(s):  
Kevin D. Little ◽  
Martin E. Hemler ◽  
Christopher S. Stipp
Keyword(s):  
Cell Surface ◽  
G Protein ◽  
Cell Activation ◽  
Surface Proteins ◽  
Membrane Microdomains ◽  
Cholesterol Depletion ◽  
Scaffolding Proteins ◽  
Intact Cells ◽  
Heterotrimeric G Protein ◽  
Vast Number

By means of a variety of intracellular scaffolding proteins, a vast number of heterotrimeric G protein–coupled receptors (GPCRs) may achieve specificity in signaling through a much smaller number of heterotrimeric G proteins. Members of the tetraspanin family organize extensive complexes of cell surface proteins and thus have the potential to act as GPCR scaffolds; however, tetraspanin-GPCR complexes had not previously been described. We now show that a GPCR, GPR56/TM7XN1, and heterotrimeric G protein subunits, Gαq, Gα11, and Gβ, associate specifically with tetraspanins and CD81, but not with other tetraspanins. CD9 Complexes of GPR56 with CD9 and CD81 remained intact when fully solubilized and were resistant to cholesterol depletion. Hence they do not depend on detergent-insoluble, raft-like membrane microdomains for stability. A central role for CD81 in promoting or stabilizing a GPR56-CD81-Gαq/11complex was revealed by CD81 immunodepletion and reexpression experiments. Finally, antibody engagement of cell surface CD81 or cell activation with phorbol ester revealed two distinct mechanisms by which GPR56-CD81-Gαq/11complexes can be dynamically regulated. These data reveal a potential role for tetraspanins CD9 and CD81 as GPCR scaffolding proteins.

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