G protein beta gamma subunits synthesized in Sf9 cells. Functional characterization and the significance of prenylation of gamma

Heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) consist of a nucleotide-binding alpha subunit and a high- affinity complex of beta and gamma subunits. There is molecular heterogeneity of beta and gamma, but the significance of this diversity is poorly understood. Different G protein beta and gamma subunits have been expressed both singly and in combinations in Sf9 cells. Although expression of individual subunits is achieved in all cases, beta gamma subunit activity (support of pertussis toxin-catalyzed ADP-ribosylation of rGi alpha 1) is detected only when beta and gamma are expressed concurrently. Of the six combinations of beta gamma tested (beta 1 or beta 2 with gamma 1, gamma 2, or gamma 3), only one, beta 2 gamma 1, failed to generate a functional complex. Each of the other five complexes has been purified by subunit exchange chromatography using Go alpha-agarose as the chromatographic matrix. We have detected differences in the abilities of the purified proteins to support ADP- ribosylation of Gi alpha 1; these differences are attributable to the gamma component of the complex. When assayed for their ability to inhibit calmodulin-stimulated type-I adenylylcyclase activity or to potentiate Gs alpha-stimulated type-II adenylylcyclase, recombinant beta 1 gamma 1 and transducin beta gamma are approximately 10 and 20 times less potent, respectively, than the other complexes examined. Prenylation and/or further carboxyl-terminal processing of gamma are not required for assembly of the beta gamma subunit complex but are indispensable for high affinity interactions of beta gamma with either G protein alpha subunits or adenylylcyclases

Computational Modeling for the Activation Cycle of G-proteins by G-protein-coupled Receptors

In this paper, we survey five different computational modeling methods. For comparison, we use the activation cycle of G-proteins that regulate cellular signaling events downstream of G-protein-coupled receptors (GPCRs) as a driving example. Starting from an existing Ordinary Differential Equations (ODEs) model, we implement the G-protein cycle in the stochastic Pi-calculus using SPiM, as Petri-nets using Cell Illustrator, in the Kappa Language using Cellucidate, and in Bio-PEPA using the Bio-PEPA eclipse plug in. We also provide a high-level notation to abstract away from communication primitives that may be unfamiliar to the average biologist, and we show how to translate high-level programs into stochastic Pi-calculus processes and chemical reactions.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005

A simplified SARS-CoV-2 detection protocol for research laboratories.

Widespread testing is required to limit the current public health crisis caused by the COVID-19 pandemic. Multiple tests protocols have been authorized by the food and drugs administration (FDA) under an emergency use authorization (EUA). The majority of these protocols are based on the gold-standard RT-qPCR test pioneered by the U.S. Centers for Disease Control and Prevention (CDC). However, there is still a widespread lack of testing in the US and many of the clinical diagnostics protocols require extensive human labor and materials that could face supply shortages and present biosafety concerns. Given the need to develop alternative reagents and approaches to provide nucleic-acid testing in the face of heightened demand and potential shortages, we have developed a simplified SARS-CoV-2 testing protocol adapted for its use in research laboratories with minimal molecular biology equipment and expertise. The protocol utilizes TRIzol to purify the viral RNA from different types of clinical specimens, requires minimal BSL-1 precautions and, given its high sensitivity, can be easily adapted to pooling samples strategies

Homologies between Signal Transducing G Proteins and ras Gene Products

The guanosine triphosphate-binding proteins (G proteins) found in a variety of tissues transduce signals generated by ligand binding to cell surface receptors into changes in intracellular metabolism. Amino acid sequences of peptides prepared by partial proteolysis of the alpha subunit of a bovine brain G protein and the alpha subunit of rod outer-segment transducin were determined. The two proteins show regions of sequence identity as well as regions of diversity. A portion of the amino-terminal peptide sequence of each protein is highly homologous with the corresponding region in the ras protein (a protooncogene product). These similarities suggest that G proteins and ras proteins may have analogous functions

Myocyte-Specific M-CAT and MEF-1 Elements Regulate G-Protein Gamma 3 Gene (γ3) Expression in Cardiac Myocytes

Little is known regarding the mechanisms that control the expression of G-protein α, β, and γ subtypes. We have previously shown that the G-protein γ3 gene is expressed in the heart, brain, lung, spleen, kidney, muscle, and testis in mice. We have also reported that the G-protein γ3 subunit is expressed in rat cardiac myocytes, but not in cardiac fibroblasts. Other studies have shown that the γ3 subunit couples to the angiotensin A1A receptor in portal vein myocytes, and has been shown to mediate β-adrenergic desensitization in cardiac myocytes treated with atorvastatin. In the present study, we evaluated G-protein γ3 promoter-luciferase reporter constructs in primary myocytes to identify key regulatory promoter regions. We identified two important regions of the promoter (upstream promoter region [UPR] and downstream promoter region [DPR]), which are required for expression in cardiac myocytes. We observed that removal of 48 bp in the UPR diminished gene transcription by 75%, and that the UPR contains consensus elements for myocyte-specific M-CAT and myocyte enhancer factor 1 (MEF-1) elements. The UPR and DPR share transcription factor elements for myocyte-specific M-CAT element. We observed that cardiac myocyte proteins bind to γ3 oligonucleotides containing transcription factor elements for myocyte-specific M-CAT and MEF-1. Myocyte-specific M-CAT proteins were supershifted with transcriptional enhancer factor-1 (TEF-1) antibodies binding to the γ3 M-CAT element, which is in agreement with reports showing that the M-CAT element binds the TEF-1 family of transcription factors. The 150 bp DPR contains three M-CAT elements, an INR element, an upstream stimulatory factor 1 element, and the transcription start site. We have shown that myocyte γ3 gene expression is regulated by myocyte-specific M-CAT and MEF-1 elements

Mice lacking the G protein γ3-subunit show resistance to opioids and diet induced obesity

Contributing to the obesity epidemic, there is increasing evidence that overconsumption of high-fat foods may be analogous to drug addiction in that the palatability of these foods is associated with activation of specific reward pathways in the brain. With this perspective, we report that mice lacking the G protein γ3-subunit (Gng3−/− mice) show resistance to high-fat diet-induced weight gain over the course of a 12-wk study. Compared with Gng3+/+ controls, female Gng3−/− mice exhibit a 40% reduction in weight gain and a 53% decrease in fat pad mass, whereas male Gng3−/− mice display an 18% reduction in weight gain and no significant decrease in fat pad mass. The basis for the lowered weight gain is related to reduced food consumption for female and male Gng3−/− mice of 13% and 14%, respectively. Female Gng3−/− mice also show a lesser preference for high-fat chow than their female Gng3+/+ littermates, suggesting an attenuated effect on a reward pathway associated with overconsumption of fat. One possible candidate is the μ-opioid receptor (Oprm1) signaling cascade. Supporting a defect in this signaling pathway, Gng3−/− mice show marked reductions in both acute and chronic morphine responsiveness, as well as increases in endogenous opioid mRNA levels in reward-related regions of the brain. Taken together, these data suggest that the decreased weight gain of Gng3−/− mice may be related to a reduced rewarding effect of the high-fat diet resulting from a defect in Oprm1 signaling and loss of the G protein γ3-subunit

Disruption of G-Protein γ₅ Subtype Causes Embryonic Lethality in Mice

<div><p>Heterotrimeric G-proteins modulate many processes essential for embryonic development including cellular proliferation, migration, differentiation, and survival. Although most research has focused on identifying the roles of the various αsubtypes, there is growing recognition that similarly divergent βγ dimers also regulate these processes. In this paper, we show that targeted disruption of the mouse <i>Gng5</i> gene encoding the γ₅ subtype produces embryonic lethality associated with severe head and heart defects. Collectively, these results add to a growing body of data that identify critical roles for the γ subunits in directing the assembly of functionally distinct G-αβγ trimers that are responsible for regulating diverse biological processes. Specifically, the finding that loss of the G-γ₅ subtype is associated with a reduced number of cardiac precursor cells not only provides a causal basis for the mouse phenotype but also raises the possibility that G-βγ₅ dependent signaling contributes to the pathogenesis of human congenital heart problems.</p></div

Genotype distribution of embryos from <i>Gng5+/−</i> intercrosses.

<p>Genotype distribution of embryos from <i>Gng5+/−</i> intercrosses.</p