New thoughts on the role of the βγ subunit in G protein signal transduction

2000 ◽  
Vol 78 (5) ◽  
pp. 537-550 ◽  
Author(s):  
Barbara Vanderbeld ◽  
Gregory M Kelly
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
G Protein Coupled Receptors ◽  
Limited Information ◽  
Α Subunit ◽  
Downstream Effectors ◽  
Receptor Signal ◽  
G Protein Coupled

Heterotrimeric G proteins are involved in numerous biological processes, where they mediate signal transduction from agonist-bound G-protein-coupled receptors to a variety of intracellular effector molecules and ion channels. G proteins consist of two signaling moieties: a GTP-bound α subunit and a βγ heterodimer. The βγ dimer, recently credited as a significant modulator of G-protein-mediated cellular responses, is postulated to be a major determinant of signaling fidelity between G-protein-coupled receptors and downstream effectors. In this review we have focused on the role of βγ signaling and have included examples to demonstrate the heterogeneity in the heterodimer composition and its implications in signaling fidelity. We also present an overview of some of the effectors regulated by βγ and draw attention to the fact that, although G proteins and their associated receptors play an instrumental role in development, there is rather limited information on βγ signaling in embryogenesis.Key words: G protein, βγ subunit, G-protein-coupled receptor, signal transduction, adenylyl cyclase.

scholarly journals Research Advances in Heterotrimeric G-Protein α Subunits and Uncanonical G-Protein Coupled Receptors in Plants

2021 ◽  
Vol 22 (16) ◽  
pp. 8678
Author(s):  
Ying Liu ◽  
Xiaoyun Wang ◽  
Danhui Dong ◽  
Luqin Guo ◽  
Xiaonan Dong ◽  
...  
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Mode Of Action ◽  
Plant Stress ◽  
G Protein Coupled Receptors ◽  
Signal Transducers ◽  
New Perspective ◽  
G Protein Coupled

As crucial signal transducers, G-proteins and G-protein-coupled receptors (GPCRs) have attracted increasing attention in the field of signal transduction. Research on G-proteins and GPCRs has mainly focused on animals, while research on plants is relatively rare. The mode of action of G-proteins is quite different from that in animals. The G-protein α (Gα) subunit is the most essential member of the G-protein signal cycle in animals and plants. The G-protein is activated when Gα releases GDP and binds to GTP, and the relationships with the GPCR and the downstream signal are also achieved by Gα coupling. It is important to study the role of Gα in the signaling pathway to explore the regulatory mechanism of G-proteins. The existence of a self-activated Gα in plants makes it unnecessary for the canonical GPCR to activate the G-protein by exchanging GDP with GTP. However, putative GPCRs have been found and proven to play important roles in G-protein signal transduction. The unique mode of action of G-proteins and the function of putative GPCRs in plants suggest that the same definition used in animal research cannot be used to study uncanonical GPCRs in plants. This review focuses on the different functions of the Gα and the mode of action between plants and animals as well as the functions of the uncanonical GPCR. This review employs a new perspective to define uncanonical GPCRs in plants and emphasizes the role of uncanonical GPCRs and Gα subunits in plant stress resistance and agricultural production.

scholarly journals Role of G-proteins in the differentiation of epiphyseal chondrocytes

2014 ◽  
Vol 53 (2) ◽  
pp. R39-R45 ◽  
Author(s):  
Andrei S Chagin ◽  
Henry M Kronenberg
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Growth Plate ◽  
Current Knowledge ◽  
Postnatal Growth ◽  
Chondrocyte Differentiation ◽  
Growth Plate Chondrocytes ◽  
Α Subunit ◽  
G Protein Coupled

Herein, we review the regulation of differentiation of the growth plate chondrocytes by G-proteins. In connection with this, we summarize the current knowledge regarding each family of G-protein α subunit, specifically, Gαs, Gαq/11, Gα12/13, and Gαi/o. We discuss different mechanisms involved in chondrocyte differentiation downstream of G-proteins and different G-protein-coupled receptors (GPCRs) activating G-proteins in the epiphyseal chondrocytes. We conclude that among all G-proteins and GPCRs expressed by chondrocytes, Gαshas the most important role and prevents premature chondrocyte differentiation. Receptor for parathyroid hormone (PTHR1) appears to be the major activator of Gαsin chondrocytes and ablation of either one leads to accelerated chondrocyte differentiation, premature fusion of the postnatal growth plate, and ultimately short stature.

scholarly journals Identification of G Protein α Subunit-Palmitoylating Enzyme

2008 ◽  
Vol 29 (2) ◽  
pp. 435-447 ◽  
Author(s):  
Ryouhei Tsutsumi ◽  
Yuko Fukata ◽  
Jun Noritake ◽  
Tsuyoshi Iwanaga ◽  
Franck Perez ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
G Protein ◽  
Adrenergic Receptor ◽  
Fluorescence Recovery After Photobleaching ◽  
G Protein Coupled Receptors ◽  
Α Subunit ◽  
Cytoplasmic Face ◽  
G Protein Α Subunit ◽  
G Protein Coupled

ABSTRACT The heterotrimeric G protein α subunit (Gα) is targeted to the cytoplasmic face of the plasma membrane through reversible lipid palmitoylation and relays signals from G-protein-coupled receptors (GPCRs) to its effectors. By screening 23 DHHC motif (Asp-His-His-Cys) palmitoyl acyl-transferases, we identified DHHC3 and DHHC7 as Gα palmitoylating enzymes. DHHC3 and DHHC7 robustly palmitoylated Gαq, Gαs, and Gαi2 in HEK293T cells. Knockdown of DHHC3 and DHHC7 decreased Gαq/11 palmitoylation and relocalized it from the plasma membrane into the cytoplasm. Photoconversion analysis revealed that Gαq rapidly shuttles between the plasma membrane and the Golgi apparatus, where DHHC3 specifically localizes. Fluorescence recovery after photobleaching studies showed that DHHC3 and DHHC7 are necessary for this continuous Gαq shuttling. Furthermore, DHHC3 and DHHC7 knockdown blocked the α1A-adrenergic receptor/Gαq/11-mediated signaling pathway. Together, our findings revealed that DHHC3 and DHHC7 regulate GPCR-mediated signal transduction by controlling Gα localization to the plasma membrane.

scholarly journals A2B Adenosine Receptor and Cancer

2019 ◽  
Author(s):  
Zhan-Guo Gao ◽  
Kenneth A. Jacobson
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Anticancer Agents ◽  
Immune Suppression ◽  
Adenosine Receptors ◽  
G Protein Coupled Receptors ◽  
Normal Tissues ◽  
Cancer Tissues ◽  
G Protein Coupled

There are four subtypes of adenosine receptors (ARs), named A1, A2A, A2B and A3, all of which are G protein-coupled receptors. The A2BAR, coupled to both Gαi and Gαq G proteins, is one of the several G-protein-coupled receptors that are expressed in a significantly higher level in some cancer tissues in comparison to adjacent normal tissues. There is growing evidence that the A2BAR plays an important role in tumor cell proliferation, angiogenesis, metastasis, and immune suppression. Thus, A2BAR antagonists are potentially novel attractive anticancer agents. Several antagonists targeting at the A2BAR are currently in clinical trials for various types of cancers. In this review, we first describe the signaling, agonists, and antagonists of the A2BAR. We further discuss the role of the A2BAR in the progression of various types cancers, and the rationale of using A2BAR antagonists in cancer therapy

The Role of Rho in G Protein-Coupled Receptor Signal Transduction

2000 ◽  
Vol 40 (1) ◽  
pp. 459-489 ◽  
Author(s):  
Valerie P. Sah ◽  
Tammy M. Seasholtz ◽  
Sarah A. Sagi ◽  
Joan Heller Brown
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Protein Coupled Receptor ◽  
Receptor Signal ◽  
G Protein Coupled

scholarly journals Interaction of class A G protein-coupled receptors with G proteins.

2004 ◽  
Vol 51 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Rafał Slusarz ◽  
Jerzy Ciarkowski
Keyword(s):  
G Protein ◽  
G Proteins ◽  
G Protein Coupled Receptors ◽  
Alpha Subunit ◽  
Protein Activation ◽  
Class A ◽  
G Protein Activation ◽  
G Protein Coupled ◽  
Receptor Dimer

A model for interaction of class A G protein-coupled receptor with the G protein G(alpha) subunit is proposed using the rhodopsin-transducin (RD/Gt) prototype. The model combines the resolved interactions/distances, essential in the active RD*/Gt system, with the structure of Gt(alpha) C-terminal peptide bound to RD* while stabilizing it. Assuming the interactions involve conserved parts of the partners, the model specifies the conserved Helix 2 non-polar X- - -X, Helix 3 DRY and Helix 7/8 NP- -Y- - F RD* motifs interacting with the Gt(alpha) C-terminal peptide, in compliance with the structure of the latter. A concomitant role of Gt(alpha) and Gt(gamma) C-termini in stabilizing RD* could possibly be resolved assuming a receptor dimer as requisite for G protein activation.

scholarly journals Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 222
Author(s):  
Agnieszka Polit ◽  
Paweł Mystek ◽  
Ewa Błasiak
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Lipid Membranes ◽  
Signaling Proteins ◽  
Heterotrimeric G Proteins ◽  
Membrane Attachment ◽  
The Individual ◽  
Multicellular Organisms ◽  
G Protein Coupled

In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein–lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.

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