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Seminars in Cancer Biology Feb 2019
Topics: Gene Expression Regulation; Guanosine Diphosphate; Guanosine Triphosphate; Humans; Neoplasms; Oncogenes; Signal Transduction; ras Proteins
PubMed: 30092255
DOI: 10.1016/j.semcancer.2018.08.005 -
Cold Spring Harbor Perspectives in... Feb 2019The guanine-nucleotide exchange factor (GEF) Son-of-Sevenless (SOS) plays a critical role in metazoan signaling by converting Ras•GDP (guanosine diphosphate) to... (Review)
Review
The guanine-nucleotide exchange factor (GEF) Son-of-Sevenless (SOS) plays a critical role in metazoan signaling by converting Ras•GDP (guanosine diphosphate) to Ras•GTP (guanosine triphosphate) in response to tyrosine kinase activation. Structural studies have shown that SOS differs from other Ras-specific GEFs in that SOS is itself activated by Ras•GTP binding to an allosteric site, distal to the site of nucleotide exchange. The activation of SOS involves membrane recruitment and conformational changes, triggered by lipid binding, that open the allosteric binding site for Ras•GTP. This is in contrast to other Ras-specific GEFs, which are activated by second messengers that more directly affect the active site. Allosteric Ras•GTP binding stabilizes SOS at the membrane, where it can turn over other Ras molecules processively, leading to an ultrasensitive response that is distinct from that of other Ras-specific GEFs.
Topics: Allosteric Site; Animals; Cell Membrane; Guanosine Diphosphate; Humans; Son of Sevenless Proteins; ras Proteins; ras-GRF1
PubMed: 29610148
DOI: 10.1101/cshperspect.a031534 -
International Journal of Molecular... Oct 2021Heterotrimeric GTP-binding proteins (G proteins), consisting of Gα, Gβ and Gγ subunits, transduce signals from a diverse range of extracellular stimuli, resulting in... (Review)
Review
Heterotrimeric GTP-binding proteins (G proteins), consisting of Gα, Gβ and Gγ subunits, transduce signals from a diverse range of extracellular stimuli, resulting in the regulation of numerous cellular and physiological functions in Eukaryotes. According to the classic G protein paradigm established in animal models, the bound guanine nucleotide on a Gα subunit, either guanosine diphosphate (GDP) or guanosine triphosphate (GTP) determines the inactive or active mode, respectively. In plants, there are two types of Gα subunits: canonical Gα subunits structurally similar to their animal counterparts and unconventional extra-large Gα subunits (XLGs) containing a C-terminal domain homologous to the canonical Gα along with an extended N-terminal domain. Both Gα and XLG subunits interact with Gβγ dimers and regulator of G protein signalling (RGS) protein. Plant G proteins are implicated directly or indirectly in developmental processes, stress responses, and innate immunity. It is established that despite the substantial overall similarity between plant and animal Gα subunits, they convey signalling differently including the mechanism by which they are activated. This review emphasizes the unique characteristics of plant Gα subunits and speculates on their unique signalling mechanisms.
Topics: Animals; GTP-Binding Protein alpha Subunits; Guanosine Diphosphate; Guanosine Triphosphate; Plant Proteins; Plants; Signal Transduction
PubMed: 34769272
DOI: 10.3390/ijms222111841 -
Science Advances Jun 2022G protein-coupled receptors (GPCRs) comprise the largest family of membrane receptors and are the most important drug targets. An agonist-bound GPCR engages...
G protein-coupled receptors (GPCRs) comprise the largest family of membrane receptors and are the most important drug targets. An agonist-bound GPCR engages heterotrimeric G proteins and triggers the exchange of guanosine diphosphate (GDP) with guanosine triphosphate (GTP) to promote G protein activation. A complete understanding of molecular mechanisms of G protein activation has been hindered by a lack of structural information of GPCR-G protein complex in nucleotide-bound states. Here, we report the cryo-EM structures of the D1 dopamine receptor and mini-G complex in the nucleotide-free and nucleotide-bound states. These structures reveal major conformational changes in Gα such as structural rearrangements of the carboxyl- and amino-terminal α helices that account for the release of GDP and the GTP-dependent dissociation of Gα from Gβγ subunits. As validated by biochemical and cellular signaling studies, our structures shed light into the molecular basis of the entire signaling events of GPCR-mediated G protein activation.
Topics: Dopamine; GTP-Binding Proteins; Guanosine Diphosphate; Guanosine Triphosphate; Protein Binding; Protein Conformation; Receptors, Dopamine
PubMed: 35687690
DOI: 10.1126/sciadv.abo4158 -
ELife May 2020During dynamic instability, self-assembling microtubules (MTs) stochastically alternate between phases of growth and shrinkage. This process is driven by the presence of...
During dynamic instability, self-assembling microtubules (MTs) stochastically alternate between phases of growth and shrinkage. This process is driven by the presence of two distinct states of MT subunits, GTP- and GDP-bound tubulin dimers, that have different structural properties. Here, we use a combination of analysis and computer simulations to study the mechanical and kinetic regulation of dynamic instability in three-dimensional (3D) self-assembling MTs. Our model quantifies how the 3D structure and kinetics of the distinct states of tubulin dimers determine the mechanical stability of MTs. We further show that dynamic instability is influenced by the presence of quenched disorder in the state of the tubulin subunit as reflected in the fraction of non-hydrolysed tubulin. Our results connect the 3D geometry, kinetics and statistical mechanics of these tubular assemblies within a single framework, and may be applicable to other self-assembled systems where these same processes are at play.
Topics: Computer Simulation; Guanosine Diphosphate; Guanosine Triphosphate; Kinetics; Microtubules; Models, Molecular; Protein Binding; Tubulin
PubMed: 32392128
DOI: 10.7554/eLife.54077 -
International Journal of Molecular... Apr 2022Guanosine nucleotide diphosphate (GDP) dissociation inhibitor 2 (GDI2) regulates the GDP/guanosine triphosphate (GTP) exchange reaction of Rab proteins by inhibiting the...
Guanosine nucleotide diphosphate (GDP) dissociation inhibitor 2 (GDI2) regulates the GDP/guanosine triphosphate (GTP) exchange reaction of Rab proteins by inhibiting the dissociation of GDP and the subsequent binding of GTP. The present study aimed to determine the function of Rab1a , and thus generated mice with a trapped gene. It was demonstrated that is essential for embryonic development. It was also found that one functional Rab1a allele was sufficient for development in a heterozygous murine embryo, whereas a double mutant led to embryonic lethality. The dissection of uteri on embryonic day (E)10.5‑14.5 yielded no homozygous embryos, indicating that homozygotes die between E10.5 to E11.5. The gene trap construct contains a β‑galactosidase/neomycin reporter gene, allowing for heterozygotes to be stained for β‑galactosidase to determine the tissue‑specific expression of Rab1a. Rab1a was found to be highly expressed in the small intestine of both adult mice and embryos, although its expression levels were low in the brains of embryos. Moreover, there was no significant change in cytokine production and survival in wild‑type and heterozygous Rab1a mice following a challenge with lipopolysaccharide. On the whole, the present study demonstrates that the disruption of the gene causes embryonic lethality and homozygotes die between E10.5 and E11.5, suggesting that is essential for the early development of mouse embryos.
Topics: Animals; Guanosine Diphosphate; Guanosine Triphosphate; Heterozygote; Mice; Proteins; beta-Galactosidase
PubMed: 35137917
DOI: 10.3892/ijmm.2022.5101 -
The Journal of Biological Chemistry Feb 1954
Topics: Guanosine Diphosphate Mannose; Nucleotides
PubMed: 13143040
DOI: No ID Found -
Cell Structure and Function Jul 2016Rab small GTPases are highly conserved master regulators of membrane traffic in all eukaryotes. The same as the activation and inactivation of other small GTPases, the... (Review)
Review
Rab small GTPases are highly conserved master regulators of membrane traffic in all eukaryotes. The same as the activation and inactivation of other small GTPases, the activation and inactivation of Rabs are tightly controlled by specific GEFs (guanine nucleotide exchange factors) and GAPs (GTPase-activating proteins), respectively. Although almost all Rab-GAPs reported thus far have a TBC (Tre-2/Bub2/Cdc16)/Rab-GAP domain in common, recent accumulating evidence has indicated the existence of a number of structurally unrelated types of Rab-GEFs, including DENN proteins, VPS9 proteins, Sec2 proteins, TRAPP complexes, heterodimer GEFs (Mon1-Ccz1, HPS1-HPS4 (BLOC-3 complex), Ric1-Rgp1 and Rab3GAP1/2), and other GEFs (e.g., REI-1 and RPGR). In this review article we provide an up-to-date overview of the structures and functions of all putative Rab-GEFs in mammals, with a special focus on their substrate Rabs, interacting proteins, associations with genetic diseases, and intracellular localizations.
Topics: Animals; Guanine Nucleotide Exchange Factors; Guanosine Diphosphate; Guanosine Triphosphate; Humans; Protein Transport; rab GTP-Binding Proteins
PubMed: 27246931
DOI: 10.1247/csf.16008 -
Cell Chemical Biology Oct 2019In this review we discuss and compare recently introduced molecules that are able to react covalently with an oncogenic mutant of KRas, KRas G12C. Two different classes... (Review)
Review
In this review we discuss and compare recently introduced molecules that are able to react covalently with an oncogenic mutant of KRas, KRas G12C. Two different classes of compounds in question have been developed, both leading to the mutant being locked in the inactive (guanosine diphosphate [GDP]-bound) state. The first are compounds that interact reversibly with the switch-II pocket (S-IIP) before covalent interaction. The second class interact in a competitive manner with the GDP/guanosine triphosphate (GTP) binding site. The fundamental physico-chemical principles of the two inhibitor classes are evaluated. For GDP/GTP-competing molecules, we show that special attention must be paid to the influence of guanine nucleotide exchange factors (GEFs) and their elevated activity in cells harboring abnormally activated Ras mutants. A new approach is suggested involving compounds that interact with the guanine binding site of the GTPase, but in a manner that is independent of the interaction of the GTPase with its cognate GEF.
Topics: Animals; Binding Sites; Guanosine Diphosphate; Guanosine Triphosphate; Humans; Small Molecule Libraries; ras Proteins
PubMed: 31378709
DOI: 10.1016/j.chembiol.2019.07.005 -
International Journal of Nanomedicine 2018Lipopolysaccharide (LPS) is widely recognized as a potent activator of monocytes/macrophages, and its effects include an altered production of key mediators, such as...
BACKGROUND
Lipopolysaccharide (LPS) is widely recognized as a potent activator of monocytes/macrophages, and its effects include an altered production of key mediators, such as inflammatory cytokines and chemokines. The involvement of G protein in mediating LPS effects has been demonstrated in murine macrophages and various cell types of human origin.
PURPOSE
The aim of the present work was to evaluate the potential of a G-protein inhibitor encapsulated in liposomes in reducing the inflammatory effects induced by LPS in monocytes/macrophages.
MATERIALS AND METHODS
Guanosine 5'--(2-thiodiphosphate) (GOT), a guanosine diphosphate analog that completely inhibits G-protein activation by guanosine triphosphate and its analogs, was encapsulated into liposomes and tested for anti-inflammatory effects in LPS-activated THP1 monocytes or THP1-derived macrophages. The viability of monocytes/macrophages after incubation with different concentrations of free GOT or liposome-encapsulated GOT was assessed by MTT assay. MAPK activation and production of IL1β, TNFα, IL6, and MCP1 were assessed in LPS-activated monocytes/macrophages in the presence or absence of free or encapsulated GOT. In addition, the effect of free or liposome-encapsulated GOT on LPS-stimulated monocyte adhesion to activated endothelium and on monocyte chemotaxis was evaluated.
RESULTS
We report here that GOT-loaded liposomes inhibited activation of MAPK and blocked the production of the cytokines IL1β, TNFα, IL6, and MCP1 induced by LPS in monocytes and macrophages. Moreover, GOT encapsulated in liposomes reduced monocyte adhesion and chemotaxis. All demonstrated events were in contrast with free GOT, which showed reduced or no effect on monocyte/macrophage activation with LPS.
CONCLUSION
This study demonstrates the potential of liposomal GOT in blocking LPS proinflammatory effects in monocytes/macrophages.
Topics: Cells, Cultured; Chemokines; Cytokines; GTP-Binding Protein alpha Subunits, Gi-Go; Guanosine Diphosphate; Humans; Inflammation; Interleukin-1beta; Lipopolysaccharides; Liposomes; Macrophage Activation; Macrophages; Monocytes; Thionucleotides; Tumor Necrosis Factor-alpha
PubMed: 29317816
DOI: 10.2147/IJN.S150918