Activation effect of extracellular calmodulin on heterotrimeric G protein in pollen plasma membrane

1999 ◽  
Vol 44 (2) ◽  
pp. 190-191
Author(s):  
Xiaodong Xu ◽  
Ligeng Ma ◽  
Ying Sun ◽  
Daye Sun
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Activation Effect ◽  
Heterotrimeric G Protein ◽  
Extracellular Calmodulin

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 Biased Signaling: Distinct Ligand-directed Plasma Membrane Signalosomes Using a Common RGS/G protein Core

2019 ◽  
Author(s):  
Timothy J. Ross-Elliott ◽  
Justin Watkins ◽  
Xiaoyi Shan ◽  
Fei Lou ◽  
Bernd Dreyer ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Lipid Rafts ◽  
Protein Complex ◽  
Heterotrimeric G Protein ◽  
Unknown Mechanism ◽  
Protein Core ◽  
Protein System ◽  
Biased Signaling ◽  
G Protein Coupled

Biased signaling occurs when different ligands that are directed at the same receptor launch different cellular outcomes. Because of their pharmacological importance, we know the most about biased ligands and little is known about other mechanisms to achieve signaling bias. In the canonical animal G protein system, endocytosis of a 7-transmembrane GPCR is mediated by arrestins to propagate or arrest cytoplasmic signaling depending on the bias. In Arabidopsis, GPCRs are not required for G protein coupled signaling because the heterotrimeric G protein complex spontaneously exchanges nucleotide. Instead, the prototype 7-transmembrane Regulator of G Signaling 1 protein AtRGS1 modulates G signaling and through ligand-dependent endocytosis, de-repression of signaling is initiated but canonical arrestins are not involved. Endocytosis initiates from two separate pools of plasma membrane: sterol-dependent domains, possibly lipid rafts, and a clathrin-accessible neighborhood, each with a select set of discriminators, activators, and newly-discovered arrestin-like adaptors. Different trafficking origins and trajectories lead to different cellular outcomes. Thus, compartmentation with its attendant signalosome architecture is a previously unknown mechanism to drive biased signaling.

scholarly journals ADP-Ribosylation Factor 6 Delineates Separate Pathways Used by Endothelin 1 and Insulin for Stimulating Glucose Uptake in 3T3-L1 Adipocytes

2001 ◽  
Vol 21 (15) ◽  
pp. 5276-5285 ◽  
Author(s):  
J. Todd R. Lawrence ◽  
Morris J. Birnbaum
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Glucose Transport ◽  
Heterotrimeric G Protein ◽  
Endothelin 1 ◽  
Adp Ribosylation ◽  
Small G Protein ◽  
Hexose Uptake ◽  
Adp Ribosylation Factor ◽  
Glucose Carrier

ABSTRACT In 3T3-L1 adipocytes, both insulin and endothelin 1 stimulate glucose transport via translocation of the GLUT4 glucose carrier from an intracellular compartment to the cell surface. Yet it remains uncertain as to whether both hormones utilize identical pathways and to what extent each depends on the heterotrimeric G protein Gαq as an intermediary signaling molecule. In this study, we used a novel inducible system to rapidly and synchronously activate expression of a dominant inhibitory form of ADP-ribosylation factor 6, ARF6(T27N), in 3T3-L1 adipocytes and assessed its effects on insulin- and endothelin-stimulated hexose uptake. Expression of ARF6(T27N) in 3T3-L1 adipocytes was without effect on the ability of insulin to stimulate either 2-deoxyglucose uptake or the translocation of GLUT4 or GLUT1 to the plasma membrane. However, the same ARF6 inhibitory mutant blocked the stimulation of hexose uptake and GLUT4 translocation in response to either endothelin 1 or an activated form of Gαq, Gαq(Q209L). These results suggest that endothelin stimulates glucose transport through a pathway that is distinct from that utilized by insulin but is likely to depend on both a heterotrimeric G protein from the Gq family and the small G protein ARF6. These data are consistent with the interpretation that endothelin and insulin stimulate functionally different pools of glucose transporters to be redistributed to the plasma membrane.

Characterization of heterotrimeric G protein complexes in rice plasma membrane

2004 ◽  
Vol 38 (2) ◽  
pp. 320-331 ◽  
Author(s):  
Chiyuki Kato ◽  
Tomohiro Mizutani ◽  
Hisanori Tamaki ◽  
Hidehiko Kumagai ◽  
Takehiro Kamiya ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Protein Complexes ◽  
Heterotrimeric G Protein
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