scholarly journals Functional and Physical Interactions among Saccharomyces cerevisiae α-Factor Receptors

2012 ◽  
Vol 11 (10) ◽  
pp. 1276-1288 ◽  
Author(s):  
Austin U. Gehret ◽  
Sara M. Connelly ◽  
Mark E. Dumont
Keyword(s):  
Saccharomyces Cerevisiae ◽  
G Protein ◽  
Dominant Negative ◽  
Negative Effects ◽  
Content Type ◽  
Functional Interactions ◽  
Wide Range ◽  
Physical Interactions ◽  
Mutant Receptors ◽  
G Protein Coupled

ABSTRACT The α-factor receptor Ste2p is a G protein-coupled receptor (GPCR) expressed on the surface of MAT a haploid cells of the yeast Saccharomyces cerevisiae . Binding of α-factor to Ste2p results in activation of a heterotrimeric G protein and of the pheromone response pathway. Functional interactions between α-factor receptors, such as dominant-negative effects and recessive behavior of constitutive and hypersensitive mutant receptors, have been reported previously. We show here that dominant-negative effects of mutant receptors persist over a wide range of ratios of the abundances of G protein to receptor and that such effects are not blocked by covalent fusion of G protein α subunits to normal receptors. In addition, we detected dominant effects of mutant C-terminally truncated receptors, which had not been previously reported to act in a dominant manner. Furthermore, coexpression of C-terminally truncated receptors with constitutively active mutant receptors results in enhancement of constitutive signaling. Together with previous evidence for oligomerization of Ste2p receptors, these results are consistent with the idea that functional interactions between coexpressed receptors arise from physical interactions between them rather than from competition for limiting downstream components, such as G proteins.

scholarly journals Dominant negative effects of a Gβ mutant on G-protein coupled inward rectifier K+channel

FEBS Letters ◽  
2006 ◽  
Vol 580 (16) ◽  
pp. 3879-3882 ◽  
Author(s):  
Qi Zhao ◽  
Abla M. Albsoul-Younes ◽  
Peng Zhao ◽  
Tohru Kozasa ◽  
Yasuko Nakajima ◽  
...  
Keyword(s):  
G Protein ◽  
Inward Rectifier ◽  
Dominant Negative ◽  
K Channel ◽  
Negative Effects ◽  
G Protein Coupled

scholarly journals Constitutively Active G Protein-coupled Receptor Mutants Block Dictyostelium Development

2005 ◽  
Vol 16 (2) ◽  
pp. 562-572 ◽  
Author(s):  
Minghang Zhang ◽  
Mousumi Goswami ◽  
Dale Hereld
Keyword(s):  
G Protein ◽  
Transmembrane Helix ◽  
Dominant Negative ◽  
G Protein Coupled Receptor ◽  
Multicellular Development ◽  
Activating Mutations ◽  
Adaptation Mechanisms ◽  
Mutant Receptors ◽  
G Protein Coupled

cAR1, a G protein-coupled receptor (GPCR) for cAMP, is required for the multicellular development of Dictyostelium. The activation of multiple pathways by cAR1 is transient because of poorly defined adaptation mechanisms. To investigate this, we used a genetic screen for impaired development to isolate four dominant-negative cAR1 mutants, designated DN1-4. The mutant receptors inhibit multiple cAR1-mediated responses known to undergo adaptation. Reduced in vitro adenylyl cyclase activation by GTPγS suggests that they cause constitutive adaptation of this and perhaps other pathways. In addition, the DN mutants are constitutively phosphorylated, which normally requires cAMP binding and possess cAMP affinities that are ∼100-fold higher than that of wild-type cAR1. Two independent activating mutations, L100H and I104N, were identified. These residues occupy adjacent positions near the cytoplasmic end of the receptor's third transmembrane helix and correspond to the (E/D)RY motif of numerous mammalian GPCRs, which is believed to regulate their activation. Taken together, these findings suggest that the DN mutants are constitutively activated and block development by turning on natural adaptation mechanisms.

scholarly journals Mini-review: antibody therapeutics targeting G protein-coupled receptors and ion channels

2020 ◽  
Vol 3 (4) ◽  
pp. 257-264
Author(s):  
Catherine J Hutchings
Keyword(s):  
Ion Channels ◽  
Research And Development ◽  
Small Molecules ◽  
G Protein ◽  
Clinical Studies ◽  
G Protein Coupled Receptors ◽  
Protein Targets ◽  
Antibody Therapeutics ◽  
Wide Range ◽  
G Protein Coupled

Abstract Antibodies are now well established as therapeutics with many additional advantages over small molecules and peptides relative to their selectivity, bioavailability, half-life and effector function. Major classes of membrane-associated protein targets include G protein-coupled receptors (GPCRs) and ion channels that are linked to a wide range of disease indications across all therapeutic areas. This mini-review summarizes the antibody target landscape for both GPCRs and ion channels as well as current progress in the respective research and development pipelines with some example case studies highlighted from clinical studies, including those being evaluated for the treatment of symptoms in COVID-19 infection.

scholarly journals WIN55,212-2, a Dual Modulator of Cannabinoid Receptors and G Protein-Coupled Inward Rectifier Potassium Channels

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 484
Author(s):  
Dongchen An ◽  
Steve Peigneur ◽  
Jan Tytgat
Keyword(s):  
Potassium Channels ◽  
Potassium Channel ◽  
G Protein ◽  
Cannabinoid Receptors ◽  
Inward Rectifier ◽  
Xenopus Laevis Oocyte ◽  
Inward Rectifier Potassium Channels ◽  
Wide Range ◽  
Cb2 Receptors ◽  
G Protein Coupled

The coupling of cannabinoid receptors, CB1 and CB2, to G protein-coupled inward rectifier potassium channels, GIRK1 and GIRK2, modulates neuronal excitability in the human brain. The present study established and validated the functional expression in a Xenopus laevis oocyte expression system of CB1 and CB2 receptors, interacting with heteromeric GIRK1/2 channels and a regulator of G protein signaling, RGS4. This ex vivo system enables the discovery of a wide range of ligands interacting orthosterically or allosterically with CB1 and/or CB2 receptors. WIN55,212-2, a non-selective agonist of CB1 and CB2, was used to explore the CB1- or CB2-GIRK1/2-RGS4 signaling cascade. We show that WIN55,212-2 activates CB1 and CB2 at low concentrations whereas at higher concentrations it exerts a direct block of GIRK1/2. This illustrates a dual modulatory function, a feature not described before, which helps to explain the adverse effects induced by WIN55,212-2 in vivo. When comparing the effects with other typical cannabinoids such as Δ9-THC, CBD, CP55,940, and rimonabant, only WIN55,212-2 can significantly block GIRK1/2. Interestingly, the inward rectifier potassium channel, IRK1, a non-G protein-coupled potassium channel important for setting the resting membrane voltage and highly similar to GIRK1 and GIRK2, is not sensitive to WIN55,212-2, Δ9-THC, CBD, CP55,940, or rimonabant. From this, it is concluded that WIN55,212-2 selectively blocks GIRK1/2.

scholarly journals The mutational landscape of human olfactory G protein-coupled receptors

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Ramón Cierco Jimenez ◽  
Nil Casajuana-Martin ◽  
Adrián García-Recio ◽  
Lidia Alcántara ◽  
Leonardo Pardo ◽  
...  
Keyword(s):  
G Protein ◽  
Olfactory Receptors ◽  
Activation Mechanism ◽  
Gene Repertoire ◽  
Structural Level ◽  
Ongoing Research ◽  
Wide Range ◽  
Natural Variants ◽  
The Impact ◽  
G Protein Coupled

Abstract Background Olfactory receptors (ORs) constitute a large family of sensory proteins that enable us to recognize a wide range of chemical volatiles in the environment. By contrast to the extensive information about human olfactory thresholds for thousands of odorants, studies of the genetic influence on olfaction are limited to a few examples. To annotate on a broad scale the impact of mutations at the structural level, here we analyzed a compendium of 119,069 natural variants in human ORs collected from the public domain. Results OR mutations were categorized depending on their genomic and protein contexts, as well as their frequency of occurrence in several human populations. Functional interpretation of the natural changes was estimated from the increasing knowledge of the structure and function of the G protein-coupled receptor (GPCR) family, to which ORs belong. Our analysis reveals an extraordinary diversity of natural variations in the olfactory gene repertoire between individuals and populations, with a significant number of changes occurring at the structurally conserved regions. A particular attention is paid to mutations in positions linked to the conserved GPCR activation mechanism that could imply phenotypic variation in the olfactory perception. An interactive web application (hORMdb, Human Olfactory Receptor Mutation Database) was developed for the management and visualization of this mutational dataset. Conclusion We performed topological annotations and population analysis of natural variants of human olfactory receptors and provide an interactive application to explore human OR mutation data. We envisage that the utility of this information will increase as the amount of available pharmacological data for these receptors grow. This effort, together with ongoing research in the study of genetic changes in other sensory receptors could shape an emerging sensegenomics field of knowledge, which should be considered by food and cosmetic consumer product manufacturers for the benefit of the general population.

scholarly journals Trans-Activation of Mutant Follicle-Stimulating Hormone Receptors Selectively Generates Only One of Two Hormone Signals

2004 ◽  
Vol 18 (4) ◽  
pp. 968-978 ◽  
Author(s):  
Inhae Ji ◽  
ChangWoo Lee ◽  
MyoungKun Jeoung ◽  
YongBum Koo ◽  
Gail A. Sievert ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
G Protein ◽  
Hormone Receptors ◽  
Transmembrane Domain ◽  
Signal Generation ◽  
Lh Receptor ◽  
Glycosyl Phosphatidylinositol ◽  
Mutant Receptors ◽  
G Protein Coupled ◽  
Hormone Signals

Abstract Previously, we reported that a liganded LH receptor (LHR) is capable of activating itself (cis-activation) and other nonliganded LHRs to induce cAMP (trans-activation). Trans-activation of the LHR raises two crucial questions. Is trans-activation unique to LHR or common to other G protein-coupled receptors? Does trans-activation stimulate phospholipase Cβ as it does adenylyl cyclase? To address these questions, two types of novel FSH receptors (FSHRs) were constructed, one defective in hormone binding and the other defective in signal generation. The FSHR, a G protein-coupled receptor, comprises two major domains, the N-terminal extracellular exodomain that binds the hormone and the membrane-associated endodomain that generates the hormone signals. For signal defective receptors, the exodomain was attached to glycosyl phosphatidylinositol (ExoGPI) or the transmembrane domain of CD8 immune receptor (ExoCD). ExoGPI and ExoCD can trans-activate another nonliganded FSH. Surprisingly, the trans-activation generates a signal to activate either adenylyl cyclase or phospholipase Cβ, but not both. These results indicate that trans-activation in these mutant receptors is selective and limited in signal generation, thus providing new approaches to investigating the generation of different hormone signals and a novel means to selectively generate a particular hormone signal. Our data also suggest that the FSHR’s exodomain could not trans-activate LHR.

scholarly journals Rescue of defective G protein–coupled receptor function in vivo by intermolecular cooperation

2010 ◽  
Vol 107 (5) ◽  
pp. 2319-2324 ◽  
Author(s):  
Adolfo Rivero-Müller ◽  
Yen-Yin Chou ◽  
Inhae Ji ◽  
Svetlana Lajic ◽  
Aylin C. Hanyaloglu ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Luteinizing Hormone Receptor ◽  
Wild Type ◽  
Gpcr Signaling ◽  
Physiological Relevance ◽  
Biosynthesis Activation ◽  
Mutant Receptors ◽  
G Protein Coupled

G protein–coupled receptors (GPCRs) are ubiquitous mediators of signaling of hormones, neurotransmitters, and sensing. The old dogma is that a one ligand/one receptor complex constitutes the functional unit of GPCR signaling. However, there is mounting evidence that some GPCRs form dimers or oligomers during their biosynthesis, activation, inactivation, and/or internalization. This evidence has been obtained exclusively from cell culture experiments, and proof for the physiological significance of GPCR di/oligomerization in vivo is still missing. Using the mouse luteinizing hormone receptor (LHR) as a model GPCR, we demonstrate that transgenic mice coexpressing binding-deficient and signaling-deficient forms of LHR can reestablish normal LH actions through intermolecular functional complementation of the mutant receptors in the absence of functional wild-type receptors. These results provide compelling in vivo evidence for the physiological relevance of intermolecular cooperation in GPCR signaling.

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