Quench-Flow Kinetic Measurement of Individual Reactions of G-Protein-Catalyzed GTPase Cycle

2002 ◽  
pp. 350-369 ◽  
Author(s):  
Suchetana Mukhopadhyay ◽  
Elliott M. Ross
Keyword(s):  
G Protein ◽  
Kinetic Measurement ◽  
Gtpase Cycle

scholarly journals Photocontrol of GTPase Cycle and Multimerization of the Small G-Protein H-Ras using Photochromic Azobenzene Derivatives

2021 ◽  
Vol 18 (4) ◽  
pp. 661-672
Author(s):  
Rufiat Nahar ◽  
Alam MD Noor A ◽  
Islam MD Alrazi ◽  
Shinsaku Maruta
Keyword(s):  
G Protein ◽  
Hypervariable Region ◽  
Cysteine Residues ◽  
Nucleotide Exchange ◽  
Ras Gtpase ◽  
Small G Protein ◽  
Sh Group ◽  
Cellular Signal ◽  
Gtpase Cycle ◽  
Azobenzene Derivatives

Ras is a small G protein known as a central regulator of cellular signal transduction that induces processes, such as cell division, transcription. The hypervariable region (HVR) is one of the functional parts of this G protein, which induces multimerization and interaction between Ras and the plasma membrane. We introduced two highly different in polarity photochromic SH group-reactive azobenzene derivatives, N-4-phenyl-azophenyl maleimide (PAM) and 4-chloroacetoamido-4-sulfo-azobenzene (CASAB), into three cysteine residues in HVR to control Ras GTPase using light. PAM stoichiometrically reacted with the SH group of cysteine residues and induced multimerization. The mutants modified with PAM exhibited reversible changes in GTPase activity accelerated by the guanine nucleotide exchange factor and GTPase activating protein and multimerization accompanied by cis- and trans-photoisomerization upon ultraviolet and visible light irradiation. CASAB was incorporated into two of the three cysteine residues in HVR but did not induce multimerization. The H-Ras GTPase modified with CASAB was photo controlled more effectively than PAM-H-Ras. In this study, we revealed that the incorporation of azobenzene derivatives into the functional site of HVR enables photo reversible control of Ras function. Our findings may contribute to the development of a method to control functional biomolecules with physiologically important roles.

G-Proteins: implications for pathophysiology and disease

1994 ◽  
Vol 131 (6) ◽  
pp. 557-574 ◽  
Author(s):  
Jan O Gordeladze ◽  
Per W Johansen ◽  
Ruth H Paulssen ◽  
Eyvind J Paulssen ◽  
Kaare M Gautvik
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein Function ◽  
Tyrosine Kinases ◽  
Point Mutations ◽  
Pharmacological Intervention ◽  
Short Term ◽  
Hormonal Activation ◽  
University Of Oslo ◽  
Gtpase Cycle

Gordeladze JO, Johansen PW, Paulssen RH, Paulssen EJ, Gautvik KM. G-Proteins: implications for pathophysiology and disease. Eur J Endocrinol 1994;131:557–74. ISSN 0804–4643 This article focuses on the involvement of G-proteins in neuroendocrine secretion, cell growth and phenotype alterations. The current concept of hormonal activation of the GTPase cycle, as well as the molecular diversity of G-protein families and receptor * G-protein * effector coupling, are described. Also described are certain G-proteins as possible proto-oncogenes and how point mutations and frame shift mutations alter G-protein function and determine the characteristics of various endocrine diseases. The article outlines in detail how receptors and G-proteins interact in prolactin and growth-hormone-secreting pituicytes, how G-proteins are involved in the growth and differentiation of preadipocytes and osteoblasts. All in all, it seems that hormonal activation through G-proteins is modulated through direct intra- and inter-signalling system cross-talk at the plasma membrane level (short-term) and through interactions on the level of transcription (HREs) from tyrosine kinases, steroid-like hormones and metabolic pathways. Pharmacological intervention to treat diseases where G-proteins are involved should take both long and short-term regulatory phenomena into consideration. JO Gordeladze, Institute of Medical Biochemistry, University of Oslo, PO Box 1112, Blindern, 0317 Oslo, Norway

scholarly journals A Physiologically Required G Protein-coupled Receptor (GPCR)-Regulator of G Protein Signaling (RGS) Interaction That Compartmentalizes RGS Activity

2013 ◽  
Vol 288 (38) ◽  
pp. 27327-27342 ◽  
Author(s):  
Wayne Croft ◽  
Claire Hill ◽  
Eilish McCann ◽  
Michael Bond ◽  
Manuel Esparza-Franco ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Signaling ◽  
Rgs Proteins ◽  
Protein Signaling ◽  
Gpcr Signaling ◽  
Additional Layer ◽  
Physiological Relevance ◽  
Gtpase Cycle ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) can interact with regulator of G protein signaling (RGS) proteins. However, the effects of such interactions on signal transduction and their physiological relevance have been largely undetermined. Ligand-bound GPCRs initiate by promoting exchange of GDP for GTP on the Gα subunit of heterotrimeric G proteins. Signaling is terminated by hydrolysis of GTP to GDP through intrinsic GTPase activity of the Gα subunit, a reaction catalyzed by RGS proteins. Using yeast as a tool to study GPCR signaling in isolation, we define an interaction between the cognate GPCR (Mam2) and RGS (Rgs1), mapping the interaction domains. This reaction tethers Rgs1 at the plasma membrane and is essential for physiological signaling response. In vivo quantitative data inform the development of a kinetic model of the GTPase cycle, which extends previous attempts by including GPCR-RGS interactions. In vivo and in silico data confirm that GPCR-RGS interactions can impose an additional layer of regulation through mediating RGS subcellular localization to compartmentalize RGS activity within a cell, thus highlighting their importance as potential targets to modulate GPCR signaling pathways.

scholarly journals Translational control by RGS2

2009 ◽  
Vol 186 (5) ◽  
pp. 755-765 ◽  
Author(s):  
Chau H. Nguyen ◽  
Hong Ming ◽  
Peishen Zhao ◽  
Lynne Hugendubler ◽  
Robert Gros ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
G Protein ◽  
Translational Control ◽  
Messenger Rna ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Rgs Proteins ◽  
Rgs Domain ◽  
Guanosine Triphosphatase ◽  
Gtpase Cycle

The regulator of G protein signaling (RGS) proteins are a family of guanosine triphosphatase (GTPase)–accelerating proteins. We have discovered a novel function for RGS2 in the control of protein synthesis. RGS2 was found to bind to eIF2Bε (eukaryotic initiation factor 2B ε subunit) and inhibit the translation of messenger RNA (mRNA) into new protein. This effect was not observed for other RGS proteins tested. This novel function of RGS2 is distinct from its ability to regulate G protein–mediated signals and maps to a stretch of 37 amino acid residues within its conserved RGS domain. Moreover, RGS2 was capable of interfering with the eIF2–eIF2B GTPase cycle, which is a requisite step for the initiation of mRNA translation. Collectively, this study has identified a novel role for RGS2 in the control of protein synthesis that is independent of its established RGS domain function.

scholarly journals Saccharomyces cerevisiae Putative G Protein, Gtr1p, Which Forms Complexes With Itself and a Novel Protein Designated as Gtr2p, Negatively Regulates the Ran/Gsp1p G Protein Cycle Through Gtr2p

Genetics ◽  
1999 ◽  
Vol 152 (3) ◽  
pp. 853-867
Author(s):  
Nobutaka Nakashima ◽  
Eishi Noguchi ◽  
Takeharu Nishimoto
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
G Protein ◽  
Amino Acid Substitution ◽  
Inhibitory Effect ◽  
The Other ◽  
Single Amino Acid ◽  
Gtpase Cycle ◽  
Novel Protein

Abstract Prp20p and Rna1p are GDP/GTP exchanging and GTPase-activating factors of Gsp1p, respectively, and their mutations, prp20-1 and rna1-1, can both be suppressed by Saccharomyces cerevisiae gtr1-11. We found that gtr1-11 caused a single amino acid substitution in Gtr1p, forming S20L, which is a putative GDP-bound mutant protein, while Gtr1p has been reported to bind to GTP alone. Consistently, gtr1-S20N, another putative GDP-bound mutant, suppressed both prp20-1 and rna1-1. On the other hand, gtr1-Q65L, a putative GTP-bound mutant, was inhibitory to prp20-1 and rna1-1. Thus, the role that Gtr1p plays in vivo appears to depend upon the nucleotide bound to it. Our data suggested that the GTP-bound Gtr1p, but not the GDP-bound Gtr1p, interacts with itself through its C-terminal tail. S. cerevisiae possesses a novel gene, GTR2, which is homologous to GTR1. Gtr2p interacts with itself in the presence of Gtr1p. The disruption of GTR2 suppressed prp20-1 and abolished the inhibitory effect of gtr1-Q65L on prp20-1. This finding, taken together with the fact that Gtr1p-S20L is a putative, inactive GDP-bound mutant, implies that Gtr1p negatively regulates the Ran/Gsp1p GTPase cycle through Gtr2p.

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

A compendium of G-protein–coupled receptors and cyclic nucleotide regulation of adipose tissue metabolism and energy expenditure

2020 ◽  
Vol 134 (5) ◽  
pp. 473-512 ◽  
Author(s):  
Ryan P. Ceddia ◽  
Sheila Collins
Keyword(s):  
Adipose Tissue ◽  
Energy Expenditure ◽  
Signaling Pathways ◽  
G Protein ◽  
Uncoupling Protein ◽  
Beige Adipocytes ◽  
Nucleotide Regulation ◽  
Ucp1 Expression ◽  
Thermogenic Adipocytes ◽  
G Protein Coupled

Abstract With the ever-increasing burden of obesity and Type 2 diabetes, it is generally acknowledged that there remains a need for developing new therapeutics. One potential mechanism to combat obesity is to raise energy expenditure via increasing the amount of uncoupled respiration from the mitochondria-rich brown and beige adipocytes. With the recent appreciation of thermogenic adipocytes in humans, much effort is being made to elucidate the signaling pathways that regulate the browning of adipose tissue. In this review, we focus on the ligand–receptor signaling pathways that influence the cyclic nucleotides, cAMP and cGMP, in adipocytes. We chose to focus on G-protein–coupled receptor (GPCR), guanylyl cyclase and phosphodiesterase regulation of adipocytes because they are the targets of a large proportion of all currently available therapeutics. Furthermore, there is a large overlap in their signaling pathways, as signaling events that raise cAMP or cGMP generally increase adipocyte lipolysis and cause changes that are commonly referred to as browning: increasing mitochondrial biogenesis, uncoupling protein 1 (UCP1) expression and respiration.

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