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Academic literature on the topic 'Eukaryotic initiation factor eIF4GI'

Author: Grafiati

Published: 6 September 2023

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Journal articles on the topic "Eukaryotic initiation factor eIF4GI"

1

Gradi, Alessandra, Hiroaki Imataka, Yuri V. Svitkin, Eran Rom, Brian Raught, Shigenobu Morino, and Nahum Sonenberg. "A Novel Functional Human Eukaryotic Translation Initiation Factor 4G." Molecular and Cellular Biology 18, no. 1 (January 1, 1998): 334–42. http://dx.doi.org/10.1128/mcb.18.1.334.

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ABSTRACT Mammalian eukaryotic translation initiation factor 4F (eIF4F) is a cap-binding protein complex consisting of three subunits: eIF4E, eIF4A, and eIF4G. In yeast and plants, two related eIF4G species are encoded by two different genes. To date, however, only one functional eIF4G polypeptide, referred to here as eIF4GI, has been identified in mammals. Here we describe the discovery and functional characterization of a closely related homolog, referred to as eIF4GII. eIF4GI and eIF4GII share 46% identity at the amino acid level and possess an overall similarity of 56%. The homology is particularly high in certain regions of the central and carboxy portions, while the amino-terminal regions are more divergent. Far-Western analysis and coimmunoprecipitation experiments were used to demonstrate that eIF4GII directly interacts with eIF4E, eIF4A, and eIF3. eIF4GII, like eIF4GI, is also cleaved upon picornavirus infection. eIF4GII restores cap-dependent translation in a reticulocyte lysate which had been pretreated with rhinovirus 2A to cleave endogenous eIF4G. Finally, eIF4GII exists as a complex with eIF4E in HeLa cells, because eIF4GII and eIF4E can be purified together by cap affinity chromatography. Taken together, our findings indicate that eIF4GII is a functional homolog of eIF4GI. These results may have important implications for the understanding of the mechanism of shutoff of host protein synthesis following picornavirus infection.

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Robert, Francis, Regina Cencic, Renying Cai, T. Martin Schmeing, and Jerry Pelletier. "RNA-tethering assay and eIF4G:eIF4A obligate dimer design uncovers multiple eIF4F functional complexes." Nucleic Acids Research 48, no. 15 (August 4, 2020): 8562–75. http://dx.doi.org/10.1093/nar/gkaa646.

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Abstract Eukaryotic cellular mRNAs possess a 5′ cap structure (m7GpppN) which plays a critical role in translation initiation mediated by eukaryotic initiation factor (eIF) 4F. The heterotrimeric eIF4F complex possesses several activities imparted by its subunits that include cap recognition (by eIF4E), RNA unwinding (eIF4A), and factor/ribosome recruitment (eIF4G). Mammalian cells have paralogs of all three eIF4F subunits and it remains an open question as to whether these all can participate in the process of ribosome recruitment. To query the activities of the eIF4F subunits in translation initiation, we adopted an RNA-tethering assay in which select subunits are recruited to a specific address on a reporter mRNA template. We find that all eIF4F subunits can participate in the initiation process. Based on eIF4G:eIF4A structural information, we also designed obligate dimer pairs to probe the activity of all combinations of eIF4G and eIF4A paralogs. We demonstrate that both eIF4GI and eIF4GII can associate with either eIF4A1 or eIF4A2 to recruit ribosomes to mRNA templates. In combination with eIF4E and eIF4E3, our results indicate the presence of up to eight eIF4F complexes that can operate in translation initiation.

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Coldwell, Mark J., Ulrike Sack, Joanne L. Cowan, Rachel M. Barrett, Markete Vlasak, Keiley Sivakumaran, and Simon J. Morley. "Multiple isoforms of the translation initiation factor eIF4GII are generated via use of alternative promoters, splice sites and a non-canonical initiation codon." Biochemical Journal 448, no. 1 (October 18, 2012): 1–11. http://dx.doi.org/10.1042/bj20111765.

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During the initiation stage of eukaryotic mRNA translation, the eIF4G (eukaryotic initiation factor 4G) proteins act as an aggregation point for recruiting the small ribosomal subunit to an mRNA. We previously used RNAi (RNA interference) to reduce expression of endogenous eIF4GI proteins, resulting in reduced protein synthesis rates and alterations in the morphology of cells. Expression of EIF4G1 cDNAs, encoding different isoforms (f–a) which arise through selection of alternative initiation codons, rescued translation to different extents. Furthermore, overexpression of the eIF4GII paralogue in the eIF4GI-knockdown background was unable to restore translation to the same extent as eIF4GIf/e isoforms, suggesting that translation events governed by this protein are different. In the present study we show that multiple isoforms of eIF4GII exist in mammalian cells, arising from multiple promoters and alternative splicing events, and have identified a non-canonical CUG initiation codon which extends the eIF4GII N-terminus. We further show that the rescue of translation in eIF4GI/eIF4GII double-knockdown cells by our novel isoforms of eIF4GII is as robust as that observed with either eIF4GIf or eIF4GIe, and more than that observed with the original eIF4GII. As the novel eIF4GII sequence diverges from eIF4GI, these data suggest that the eIF4GII N-terminus plays an alternative role in initiation factor assembly.

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Yanagiya, Akiko, Yuri V. Svitkin, Shoichiro Shibata, Satoshi Mikami, Hiroaki Imataka, and Nahum Sonenberg. "Requirement of RNA Binding of Mammalian Eukaryotic Translation Initiation Factor 4GI (eIF4GI) for Efficient Interaction of eIF4E with the mRNA Cap." Molecular and Cellular Biology 29, no. 6 (December 29, 2008): 1661–69. http://dx.doi.org/10.1128/mcb.01187-08.

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ABSTRACT Eukaryotic mRNAs possess a 5′-terminal cap structure (cap), m7GpppN, which facilitates ribosome binding. The cap is bound by eukaryotic translation initiation factor 4F (eIF4F), which is composed of eIF4E, eIF4G, and eIF4A. eIF4E is the cap-binding subunit, eIF4A is an RNA helicase, and eIF4G is a scaffolding protein that bridges between the mRNA and ribosome. eIF4G contains an RNA-binding domain, which was suggested to stimulate eIF4E interaction with the cap in mammals. In Saccharomyces cerevisiae, however, such an effect was not observed. Here, we used recombinant proteins to reconstitute the cap binding of the mammalian eIF4E-eIF4GI complex to investigate the importance of the RNA-binding region of eIF4GI for cap interaction with eIF4E. We demonstrate that chemical cross-linking of eIF4E to the cap structure is dramatically enhanced by eIF4GI fragments possessing RNA-binding activity. Furthermore, the fusion of RNA recognition motif 1 (RRM1) of the La autoantigen to the N terminus of eIF4GI confers enhanced association between the cap structure and eIF4E. These results demonstrate that eIF4GI serves to anchor eIF4E to the mRNA and enhance its interaction with the cap structure.

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Caron, Sandrine, Martine Charon, Elisabeth Cramer, Nahum Sonenberg, and Isabelle Dusanter-Fourt. "Selective Modification of Eukaryotic Initiation Factor 4F (eIF4F) at the Onset of Cell Differentiation: Recruitment of eIF4GII and Long-Lasting Phosphorylation of eIF4E." Molecular and Cellular Biology 24, no. 11 (June 1, 2004): 4920–28. http://dx.doi.org/10.1128/mcb.24.11.4920-4928.2004.

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ABSTRACT mRNA translation is mainly regulated at the level of initiation, a process that involves the synergistic action of the 5′ cap structure and the 3′ poly(A) tail at the ends of eukaryotic mRNA. The eukaryote initiation factor 4G(eIF4G) is a pivotal scaffold protein that forms a critical link between mRNA cap structure, poly(A) tail, and the small ribosomal subunit. There are two functional homologs of eIF4G in mammals, the original eIF4G, renamed eIF4GI, and eIF4GII that functionally complements eIF4GI. To date, biochemical and functional analysis have not identified differential activities for eIF4GI and eIF4GII. In this report, we demonstrate that eIF4GII, but not eIF4GI, is selectively recruited to capped mRNA at the onset of cell differentiation. This recruitment is coincident with a strong and long-lasting phosphorylation of eIF4E and the release of 4E-BP1, a suppressor of eIF4E function, from the cap structure, without a concomitant change in 4E-BP1's phosphorylation. Our data further indicate that cytokines such as thrombopoietin can differentially regulate eIF4GI/II activities. These results provide the first evidence that eIF4GI/II does fulfill selective roles in mammalian cells.

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Álvarez, Enrique, Luis Menéndez-Arias, and Luis Carrasco. "The Eukaryotic Translation Initiation Factor 4GI Is Cleaved by Different Retroviral Proteases." Journal of Virology 77, no. 23 (December 1, 2003): 12392–400. http://dx.doi.org/10.1128/jvi.77.23.12392-12400.2003.

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ABSTRACT The initiation factor eIF4G plays a central role in the regulation of translation. In picornaviruses, as well as in human immunodeficiency virus type 1 (HIV-1), cleavage of eIF4G by the viral protease leads to inhibition of protein synthesis directed by capped cellular mRNAs. In the present work, cleavage of both eIF4GI and eIF4GII has been analyzed by employing the proteases encoded within the genomes of several members of the family Retroviridae, e.g., Moloney murine leukemia virus (MoMLV), mouse mammary tumor virus, human T-cell leukemia virus type 1, HIV-2, and simian immunodeficiency virus. All of the retroviral proteases examined were able to cleave the initiation factor eIF4GI both in intact cells and in cell-free systems, albeit with different efficiencies. The eIF4GI hydrolysis patterns obtained with HIV-1 and HIV-2 proteases were very similar to each other but rather different from those obtained with MoMLV protease. Both eIF4GI and eIF4GII were cleaved very efficiently by the MoMLV protease. However, eIF4GII was a poor substrate for HIV proteases. Proteolytic cleavage of eIF4G led to a profound inhibition of cap-dependent translation, while protein synthesis driven by mRNAs containing internal ribosome entry site elements remained unaffected or was even stimulated in transfected cells.

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Coldwell, Mark J., and Simon J. Morley. "Specific Isoforms of Translation Initiation Factor 4GI Show Differences in Translational Activity." Molecular and Cellular Biology 26, no. 22 (September 18, 2006): 8448–60. http://dx.doi.org/10.1128/mcb.01248-06.

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ABSTRACT The eukaryotic initiation factor (eIF) 4GI gene locus (eIF4GI) contains three identified promoters, generating alternately spliced mRNAs, yielding a total of five eIF4GI protein isoforms. Although eIF4GI plays a critical role in mRNA recruitment to the ribosomes, little is known about the functions of the different isoforms, their partner binding capacities, or the role of the homolog, eIF4GII, in translation initiation. To directly address this, we have used short interfering RNAs (siRNAs) expressed from DNA vectors to silence the expression of eIF4GI in HeLa cells. Here we show that reduced levels of specific mRNA and eIF4GI isoforms in HeLa cells promoted aberrant morphology and a partial inhibition of translation. The latter reflected dephosphorylation of 4E-BP1 and decreased eIF4F complex levels, with no change in eIF2α phosphorylation. Expression of siRNA-resistant Myc-tagged eIF4GI isoforms has allowed us to show that the different isoforms exhibit significant differences in their ability to restore translation rates. Here we quantify the efficiency of eIF4GI promoter usage in mammalian cells and demonstrate that even though the longest isoform of eIF4GI (eIF4GIf) was relatively poorly expressed when reintroduced, it was more efficient at promoting the translation of cellular mRNAs than the more highly expressed shorter isoforms used in previous functional studies.

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Patel, Krishnaben, Grishma K. Shah, Sai Shilpa Kommaraju, and Woon-Kai Low. "Investigation of the conserved glutamate immediately following the DEAD box in eukaryotic translation initiation factor 4AI." Biochemistry and Cell Biology 92, no. 1 (February 2014): 33–42. http://dx.doi.org/10.1139/bcb-2013-0076.

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The DExD-box family (DEAD-box) of proteins was surveyed for eukaryotic translation initiation factor 4A-specific sequences surrounding the DEAD box. An eIF4A-unique glutamate residue (E186 in eIF4AI) was identified immediately following the D-E-A-D sequence in eIF4AI, II, and III that was found to be conserved from yeast to Man. Mutation to a selection of alternative amino acids was performed within recombinant eIF4AI expressed in Escherichia coli and mutant proteins were surveyed for RNA-dependent ATPase activity. The mutants were also investigated for changes in activity in the presence of the two eIF4AI-binding domains of eIF4GI as well as for co-purification ability to these two domains. The E186 residue was found to be of significance for RNA-dependent ATPase activity for eIF4AI alone and in the presence of eIF4AI-binding domains of eIF4GI through point-mutation analysis. Furthermore, binding interactions between eIF4AI and eIF4GI domains were also significantly influenced by mutation of E186, as observed through co-purification assays. Thus, this residue appears to be of functional significance for eIF4A.

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Neff, Carrie L., and Alan B. Sachs. "Eukaryotic Translation Initiation Factors 4G and 4A from Saccharomyces cerevisiae Interact Physically and Functionally." Molecular and Cellular Biology 19, no. 8 (August 1, 1999): 5557–64. http://dx.doi.org/10.1128/mcb.19.8.5557.

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ABSTRACT The initiation of translation in eukaryotes requires several multisubunit complexes, including eukaryotic translation initiation factor 4F (eIF4F). In higher eukaryotes eIF4F is composed of the cap binding protein eIF4E, the adapter protein eIF4G, and the RNA-stimulated ATPase eIF4A. The association of eIF4A withSaccharomyces cerevisiae eIF4F has not yet been demonstrated, and therefore the degree to which eIF4A’s conserved function relies upon this association has remained unclear. Here we report an interaction between yeast eIF4G and eIF4A. Specifically, we found that the growth arrest phenotype associated with three temperature-sensitive alleles of yeast eIF4G2 was suppressed by excess eIF4A and that this suppression was allele specific. In addition, in vitro translation extracts derived from an eIF4G2 mutant strain could be heat inactivated, and this inactivation could be reversed upon the addition of recombinant eIF4A. Finally, in vitro binding between yeast eIF4G and eIF4A was demonstrated, as was diminished binding between mutant eIF4G2 proteins and eIF4A. In total, these data indicate that yeast eIF4G and eIF4A physically associate and that this association performs an essential function.

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Li, Qiyu, Hiroaki Imataka, Shigenobu Morino, George W. Rogers, Nancy J. Richter-Cook, William C. Merrick, and Nahum Sonenberg. "Eukaryotic Translation Initiation Factor 4AIII (eIF4AIII) Is Functionally Distinct from eIF4AI and eIF4AII." Molecular and Cellular Biology 19, no. 11 (November 1, 1999): 7336–46. http://dx.doi.org/10.1128/mcb.19.11.7336.

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ABSTRACT Eukaryotic initiation factor 4A (eIF4A) is an RNA-dependent ATPase and ATP-dependent RNA helicase that is thought to melt the 5′ proximal secondary structure of eukaryotic mRNAs to facilitate attachment of the 40S ribosomal subunit. eIF4A functions in a complex termed eIF4F with two other initiation factors (eIF4E and eIF4G). Two isoforms of eIF4A, eIF4AI and eIF4AII, which are encoded by two different genes, are functionally indistinguishable. A third member of the eIF4A family, eIF4AIII, whose human homolog exhibits 65% amino acid identity to human eIF4AI, has also been cloned from Xenopus and tobacco, but its function in translation has not been characterized. In this study, human eIF4AIII was characterized biochemically. While eIF4AIII, like eIF4AI, exhibits RNA-dependent ATPase activity and ATP-dependent RNA helicase activity, it fails to substitute for eIF4AI in an in vitro-reconstituted 40S ribosome binding assay. Instead, eIF4AIII inhibits translation in a reticulocyte lysate system. In addition, whereas eIF4AI binds independently to the middle and carboxy-terminal fragments of eIF4G, eIF4AIII binds to the middle fragment only. These functional differences between eIF4AI and eIF4AIII suggest that eIF4AIII might play an inhibitory role in translation under physiological conditions.

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Dissertations / Theses on the topic "Eukaryotic initiation factor eIF4GI"

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Li, Qiyu. "Eukaryotic translation initiation factor eIF4AIII is functionally distinct from eIF4AI and eIF4AII." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0035/MQ64391.pdf.

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Li, Qiyu 1972. "Eukaryotic translation initiation factor eIF4AIII is functionally distinct from eIF4AI AND eIF4AII." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30687.

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eIF4A is an RNA-dependent ATPase and ATP-dependent RNA helicase that is thought to melt the 5' proximal secondary structure of eukaryotic mRNAs to facilitate attachment of the 40S ribosomal subunit. eIF4A functions in a complex with two other initiation factors (eIF4E and eIF4G). Two isoforms of eIF4A, eIF4AI and eIF4AII, are functionally indistinguishable. A third member of the eIF4A family, eIF4AIII, whose human homolog exhibits 65% amino acid identity to human eIF4AI, has also been cloned from Xenopus and tobacco, but its function in translation has not been characterized. In this report, human eIF4AIII is characterized biochemically. While eIF4AIII, like eIF4AI, exhibits RNA-dependent ATPase activity and ATP-dependent RNA helicase activity, it fails to substitute for eIF4AI in an in vitro reconstituted 40S ribosome binding assay. Instead, eIF4AIII inhibits translation in a reticulocyte lysate system. In addition, whereas eIF4AI binds independently to the middle and carboxy-terminal fragments of eIF4G, eIF4AIII binds to the middle fragment only. These functional differences between eIF4AI and eIF4AIII suggest that eIF4AIII plays an inhibitory role in translation under physiological conditions.

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Shahbazian, David. "Eukaryotic initiation factor 4B (eIF4B) : regulation by signaling pathways and its role in translation." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115902.

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Due to the high energetic expenditure for the cell, the protein biosynthesis in eukaryotes is an extensively controlled process predominantly regulated at the ribosomal biogenesis and translation initiation steps. The ribosomal biogenesis defines the global translational aptitude of the cell. It is a mainly nucleolar process which is regulated at multiple steps (e.g. transcription, rRNA processing and modification, ribosomal protein translation etc). However, the most extensively regulated and the rate limiting step of translation is the initiation. Multiple eukaryotic translation initiation factors (eIFs) function to facilitate this priming step of translation. The initial recognition of the mRNA molecule happens through the 5' cap structure found in all mRNAs of nuclear origin. This event is mediated through the recruitment of heterotrimeric complex eIF4F consisting of cap-binding protein eIF4E, scaffolding protein eIF4G and the RNA helicase eIF4A unwinding secondary structures found in 5'UTR of mRNA and thus thought to facilitate the scanning process. The helicase activity of elF4F complex or of eIF4A alone is further potentiated by eIF4B in vitro. The latter protein is at the focus of present thesis.
Signal transduction regulates multiple cellular processes including mitogenesis, differentiation, apoptosis, chemotaxis etc. Signaling pathways also regulate ribosomal biogenesis to coordinate mitogenic cues, nutrient and energy availability with the translational capacity of the cells. Mounting evidence links PI3K-Akt-mTOR and Ras-MAPK cascades to the translational control. In this thesis, I show that PI3K/mTOR and MAP kinase cascades converge to phosphorylate eIF4B on Ser422. This phosphorylation results in an increased interaction with eIF3, an essential factor bridging between eIF4F and the small ribosomal subunit. Physiological significance of eIF4B phosphorylation on Ser422 has been demonstrated by the stimulatory effect of eIF4B Ser422Asp phosphomimetic mutant on cap-dependent translation. Taken together, this represents a new paradigm of translational control mechanism regulated by signaling crosstalk. The function of eIF4B in vitro is well characterized but its in vivoeffects are disputed in literature. To address this I established HeLa cell line stably expressing shRNA targeting eIF4B. eIF4B silencing inhibits proliferation rates and anchorage-independent growth. Expression of luciferase reporter gene containing 5' terminal oligopyrimidine tract (TOP) is selectively repressed in eIF4B-silenced cells and can be rescued by exogenous eIF4B regardless of Ser422 phosphorylation status. Moreover, the de novo synthesis rates of endogenous ribosomal proteins in serum starved cultures recapitulate the luciferase reporter assay data. Utilizing polysomal analysis, I was able to show more significant inhibition of translation initiation in serum starved eIF4B-silenced cells. Our attempt to discover novel eIF4B-interacting proteins by Mass Spectrometry approach led to the identification of nucleolar RNA helicase DDX21. Confocal microscopy has shown partial co-localization of tagged eIF4B and DDX21 in nucleolar periphery. Pulse chase experiments metabolically labeling rRNA show an attenuated 28S rRNA production and concomitant accumulation of 36S intermediates in eIF4B-silenced cells. Since ribosomal biogenesis is highly coordinated process and requires strict stoichiometry maintenance of ribosomal components the observed inhibition of rRNA processing could be consequential to the decreased ribosomal protein expression. However, given the fact that eIF4B is associated with the nucleolar pre-ribosomal particle complexes its direct effect on rRNA processing cannot be ruled out. Regulation of ribosomal biogenesis by translation initiation factor may represent an important control mechanism allowing cells to co-ordinate these two processes.

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Combe, Jonathan P. "The isolation and functional analysis of the eukaryotic translation initiation factor eIF4E from tobacco." Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/29777.

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An investigation into the regulatory characteristics of plant eIF4E was initiated. Two cDNAs, NeIF4E1 and NeIF4E2 encoding putative tobacco eIF4E homologues were isolated from a pollen cDNA library. NeIF4E2 contained an incomplete open reading frame (ORF) truncated at the 5' terminus, whereas NeIF4E2 consisted of a complete ORF, encoding a predicted 222 amino acid polypeptide. The predicted polypeptide sequences of NeIF4E1 and NeIF4E2 were 95% identical. The complete NeIF4E1 translation product was 67, 69 and 64% identical to wheat, rice and the Arabidopsis eIF4E, respectively. The expression pattern of NeIF4E in tobacco was investigated at the mRNA and protein level. The latter involved the raising of rabbit polyclonal antibodies against bacterially expressed NeIF4E1 protein. Both NeIF4E1 mRNA and protein were detected in all tissues and developmental stages investigated. To investigate whether NeIF4E was essential for tobacco translation, NeIF4E1 antisense constructs, incorporating either the constitutive CaMV 35S and pollen-specific lat52 promoter, were introduced into tobacco by stable genetic transformation. No visible phenotype was obtained with either construct, although NeIF4E protein was reduced by more than 50% of wild type levels with the CaMV35S-NeIF4E1-antisense transgene. The effect of overexpressing NeIF4E1 on plant gene expression was also investigated. Sense NeIF4E1 constructs containing the CaMV35S and lat52 promoters were transiently expressed, with a luciferase test plasmid, in leaves and pollen respectively. Luciferase gene expression was consistently inhibited by NeIF4E1 overexpression. Further experiments with mutant NeIF4E derivatives indicated the inhibition was exerted by the NeIF4E polypeptide not the transcript.

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Ruud, Kelley Astrid. "Identification and characterization of a novel cap-binding protein from Arabidopsis thaliana and of the wheat eukaryotic initiation factor eIF4G /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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Jones, Grant D. "Discovery, Phylogenetic Analysis, and Functional Characterization of a Unique Family of Eukaryotic Translation Initiation Factor 4E, eIF4E, From Amphidinium carterae, a Marine Dinoflagellate." Thesis, University of Maryland, Baltimore, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10118645.

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This study investigates the eIF4E family members in Dinoflagellates. Dinoflagellates are eukaryotic algae with large genomes and a minimal role for transcriptional regulation. All mRNA in dinoflagellates is trans -spliced with a 22-nucleotide 5'-spliced-leader sequence bearing a multi-methylated cap. Like other eukaryotes, dinoflagellates encode multiple eIF4E family members that are anticipated to fulfill a range of functions. Three distinct and novel clades of eIF4E have been recognized in dinoflagellates that are separate from the three metazoan classes of eIF4E. The dinoflagellate Amphidinium carterae encodes eight eIF4E family members while Karlodinium veneficum encodes fifteen eIF4E family members. I assayed six of these family members from A. carterae for expression levels, m⁷GTP binding, yeast knockout complementation and affinity for three mRNA cap analogs using surface plasmon resonance (SPR). Transcripts of each are expressed through a diel cycle, but only eIF4E-1 family members and eIF4E-2a are expressed at the level of protein. Recombinant eIF4E-1 family members and eIF4E-3a, but not eIF4E-2a, are able to bind to m⁷GTP-agarose beads. Of the clade 1 eIF4Es, only eIF4E-1a and -1d1 complement a S. cerevisiae strain conditionally deficient in functional eIF4E, consistent with their function as translation initiation factors. However, only eIF4E-1a can be recovered from A. carterae extracts by m⁷GTP affinity binding. Using SPR analysis, the affinity of A. carterae eIF4E-1a for m⁷GTP is lower than that of murine eIF4E-1A. By the same analysis, A. carterae eIF4E-1a has a higher affinity for m⁷GpppG than m⁷GTP. In addition, K. veneficum eIF4E-1a1 displays many of the same characteristics as A. carterae eIF4E-1a. Four eIF4E-1 and one eIF4E-2 family members from K. veneficum were characterized for m⁷GTP binding capacity, only the eIF4E-1 family members can be pulled down with m⁷GTP. Three eIF4E family members were tested for their ability to interact with a putative eIF4E-interacting protein, although none interacted. Overall, the eIF4E-1a sub-clade emerges with characteristics consistent with the role of a prototypical translation initiation factor. These initial analyses will allow for a better understanding of specific translational control of gene expression through mRNA recruitment in the unique dinoflagellate lineage.

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Metz, Anneke Maria. "Function of the wheat eukaryotic initiation factors eIF(ISO)4G and eIF4B in translation /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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Green, Simon Richard. "Molecular analysis of eukaryotic initiation factor 2#alpha#." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330170.

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Bottari, Nicolas. "Putative role of eukaryotic initiation factor 4AIII in the nucleus." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78325.

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Nonsense-mediated decay (NMD) is a cellular event by which messenger RNAs (mRNA) possessing a premature termination codon (PTC) are rapidly degraded to avoid production of incomplete proteins. NMD is a translation-dependent cytoplasmic and nucleus-associated event. Eukaryotic initiation factor 4AIII (eIF4AIII) is a RNA-helicase protein found mostly in the nucleus. It is related to the eIF4AI and eIF4AII proteins, which are localized to the cytoplasm where they are involved in translation initiation. The role of eIF4AIII in nucleus-associated NMD was investigated in this work. HeLa cells were treated with small interfering RNA (siRNA) targeted against eIF4AIII. Immunoblot analysis revealed 45 to 93% knockdown of eIF4AM protein levels compared to nontransfected cells. RNA from siRNA-treated HeLa cells stably transfected with the T-cell receptor-beta (TCR-beta) gene possessing a PTC was analyzed by Northern blotting. TCR-beta mRNA levels were reduced in nontransfected cells, increased in eIF4AIII knockdown cells, and reduced in exogenous HA-eIF4AIII rescued cells. A helicase-dead mutant of eIF4AIII (PRRVAA) also rescues the TCR-beta mRNA decay. Pulse-labelling experiments using radioactive 35S-methionine revealed that eIF4AIII knockdown cells had a reduced (~50%) translational rate compared to nontransfected cells. This data suggests that eIF4AIII is involved in nucleus-associated nonsense-mediated decay and also has a role in general translation.

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Fennell, Clare. "Characterisation of the eukaryotic initiation factor 2alpha kinases of Plasmodium falciparum." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/527/.

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Malaria remains a devastating disease with respect to both mortality and the constraints it places on the economic development of the countries in which it is endemic. Our laboratory is seeking new antimalarial targets, by characterising the protein kinases of the most lethal human malaria parasite, Plasmodium falciparum. As central components of many diverse signalling pathways, protein kinases are crucial for the control of proliferation and differentiation in other eukaryotes; we hypothesise that they play similar roles in P. falciparum. The life cycle of P. falciparum is complex, consisting of a series of tightly controlled stages of division and differentiation. In the related apicomplexan parasite Toxoplasma gondii, stress stimuli have been implicated in an important differentiation step, from rapidly dividing tachyzoites, to quiescent bradyzoites (which enable immune evasion). Evidence suggests that stress may also contribute to an essential differentiation stage, gametocytogenesis, in P. falciparum. In yeast and metazoans, part of the stress response is mediated through phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha), which results in selective translation of mRNAs encoding stress response proteins. Post-transcriptional control of gene expression is suspected to play an important role in P. falciparum. Importantly, the Goldberg laboratory recently demonstrated that similarly, in P. falciparum the eIF2alpha orthologue is phosphorylated in response to starvation. Here we identify the P. falciparum orthologue of the translation initiation factor eIF2alpha and provide bioinformatic evidence for the presence of three eIF2alpha kinases in P. falciparum; PfeIK1, PfeIK2 and PfPK4, only one of which (PfPK4) has been described previously (Mohrle et al., 1997). We show that one of the novel eIF2alpha kinases, PfeIK1, is able to phosphorylate P. falciparum eIF2alpha in vitro. In addition, initial experiments support previous observations that PfPK4 is indeed an active protein kinase (Mohrle et al., 1997). We present evidence that PfPK4 is essential for asexual growth, which precludes straightforward reverse genetics studies aiming to determine its possible role in gametocytogenesis. In contrast, transgenic parasites allowed us to show that neither PfeIK1 nor PfeIK2 are required for asexual growth, or sexual development of the parasite in the mosquito vector. However, preliminary evidence (requiring confirmation) may indicate that parasites lacking PfeIK1 over-express PfPK4, which would suggest that PfeIK1 may play an important function in the parasite. This study strongly suggests that a mechanism for versatile regulation of translation by several kinases with a similar catalytic domain, but distinct regulatory domains, is conserved in P. falciparum.

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Books on the topic "Eukaryotic initiation factor eIF4GI"

1

Vasilescu, S. Structure function and intracellular localisation of the eukaryotic initiation factor eIF4E in theyeast Saccharomyces cerevisiae. Manchester: UMIST, 1996.

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Gordon, Edys D. Studies on the hypusine-containing protein, eukaryotic initiation factor, EIF-4D. 1987.

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(Editor), A. Y. Liu, and K. Y. Chen (Editor), eds. Hypusyne Formation on Eukaryotic Initiation Factor 5A: Biochemistry & Function (Biological Signals Ser. Series, 3). S Karger Pub, 1997.

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Book chapters on the topic "Eukaryotic initiation factor eIF4GI"

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You, Tao, George M. Coghill, and Alistair J. P. Brown. "Eukaryotic Translation Initiation Factor Interactions." In Encyclopedia of Systems Biology, 675–78. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-9863-7_831.

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Gupta, Naba K., Mir F. Ahmad, Debopam Chakrabarti, and Nargis Nasrin. "Roles of Eukaryotic Initiation Factor 2 and Eukaryotic Initiation Factor 2 Ancillary Protein Factors in Eukaryotic Protein Synthesis Initiation." In Translational Regulation of Gene Expression, 287–334. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-5365-2_14.

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Proud, Christopher G. "Regulation of Eukaryotic Initiation Factor eIF2B." In Signaling Pathways for Translation, 95–114. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56688-2_4.

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Westermann, P., R. Benndorf, G. Lutsch, H. Bielka, and O. Nygård. "Arrangement of Eukaryotic Initiation Factor 3 and Messenger RNA within Preinitiation Complexes." In Springer Series in Molecular Biology, 642–57. New York, NY: Springer New York, 1986. http://dx.doi.org/10.1007/978-1-4612-4884-2_37.

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Prostko, Christopher R., Margaret A. Brostrom, and Charles O. Brostrom. "Reversible phosphorylation of eukaryotic initiation factor 2α in response to endoplasmic reticular signaling." In Reversible Protein Phosphorylation in Cell Regulation, 255–65. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2600-1_24.

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Riera, Marta, Nerea Roher, Francesc Miró, Carles Gil, Ramon Trujillo, José Aguilera, Maria Plana, and Emilio Itarte. "Association of protein kinase CK2 with eukaryotic translation initiation factor eIF-2 and with grp94/endoplasmin." In A Molecular and Cellular View of Protein Kinase CK2, 97–104. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4419-8624-5_12.

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Kaempfer, Raymond. "The Interaction between Viral Messenger RNA and Eukaryotic Initiation Factor 2, a Protein Involved in Translational Control." In Viral Messenger RNA, 21–48. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2585-7_2.

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Jennings, Martin D., and Graham D. Pavitt. "Quantifying the Binding of Fluorescently Labeled Guanine Nucleotides and Initiator tRNA to Eukaryotic Translation Initiation Factor 2." In Methods in Molecular Biology, 89–99. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1975-9_6.

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Caraglia, Michele, Pierosandro Tagliaferri, Alfredo Budillon, and Alberto Abbruzzese. "Post-Translational Modifications of Eukaryotic Initiation Factor-5A (eIF-5a) as a New Target for Anti-Cancer Therapy." In Advances in Nutrition and Cancer 2, 187–98. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4757-3230-6_16.

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Green, Simon R., and Michael B. Mathews. "The phosphorylation of eukaryotic initiation factor 2 and its role in the regulation of translation during viral infection." In Post-transcriptional Control of Gene Expression, 177–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-60929-9_15.

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Conference papers on the topic "Eukaryotic initiation factor eIF4GI"

1

Li, Yikun, Junghui Koo, Songqing Fan, Ping Yue, Taofeek K. Owonikoko, Suresh S. Ramalingam, Fadlo R. Khuri, and Shi-Yon Sun. "Abstract 1953: Elevated eukaryotic translation initiation factor 4E (eIF4E) is involved in erlotinib resistance." In Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.am2011-1953.

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Jaiswal, Praveen, Sweaty Koul, Nallasivam Palanisamy, and Hari K. Koul. "Abstract 4385: Eukaryotic translation initiation factor 4 gamma 1 (EIF4G1): A target for cancer therapeutic intervention." In Proceedings: AACR Annual Meeting 2019; March 29-April 3, 2019; Atlanta, GA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1538-7445.sabcs18-4385.

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Jaiswal, Praveen, Sweaty Koul, Nallasivam Palanisamy, and Hari K. Koul. "Abstract 4385: Eukaryotic translation initiation factor 4 gamma 1 (EIF4G1): A target for cancer therapeutic intervention." In Proceedings: AACR Annual Meeting 2019; March 29-April 3, 2019; Atlanta, GA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1538-7445.am2019-4385.

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Zuberek, Joanna, Janusz Stępiński, Anna Niedzwiecka, Ryszard Stolarski, Harri Salo, Harri Lönnberg, and Edward Darżynkiewicz. "Synthesis of tetraribonucleotide cap analogue m7GpppAm2'pUm2'pAm2' and its interaction with eukaryotic initiation factor eIF4E." In XIIth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2002. http://dx.doi.org/10.1135/css200205399.

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Jaiswal, Praveen K., Sweaty Koul, Prakash Srinivasan Timiri Shanmugam, and Hari K. Koul. "Abstract 4436: Eukaryotic translation initiation factor 4 gamma 1 (EIF4G1) is upregulated modulates prostate cancer growth and proliferation." In Proceedings: AACR Annual Meeting 2018; April 14-18, 2018; Chicago, IL. American Association for Cancer Research, 2018. http://dx.doi.org/10.1158/1538-7445.am2018-4436.

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de la Parra, Columba, Elisa Otero-Franqui, and Suranganie Dharmawardhane. "Abstract 1988: Increased expression of eukaryotic protein synthesis initiation factor eIF4G by the daidzein metabolite equol may contribute to breast cancer malignancy." In Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-1988.

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Reich, Siegfried H., Peggy A. Thompson, Justin T. Ernst, Boreth Eam, Nathan P. Young, Sarah Fish, Joan Chen, et al. "Abstract DDT02-05: eFT226: A selective and highly potent inhibitor of eukaryotic initiation factor 4A (eIF4A), a novel approach for the treatment of cancer." In Proceedings: AACR Annual Meeting 2018; April 14-18, 2018; Chicago, IL. American Association for Cancer Research, 2018. http://dx.doi.org/10.1158/1538-7445.am2018-ddt02-05.

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Chakravarti, Nitin, Carla L. Warneke, Marcella M. Johnson, Michael A. Davies, and Victor G. Prieto. "Abstract 1486: Increased expression and phosphorylation of eukaryotic initiation factor 4E (eIF4E) and 4E-binding protein (4E-BP1) correlates with disease progression and high risk clinical/pathological features in melanoma." In Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-1486.

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Ramamurthy, Vidya priyadarsini, Senthilmurugan Ramalingam, Lalji Gediya, and Vincent C. O. Njar. "Abstract 2704: Simultaneous targeting of androgen receptor (AR) and Eukaryotic Initiation Factor 4E (eIF4E) dependent translation initiation by RAMBA Retinamides promotes apoptosis and impedes cell growth, cell proliferation and matrix invasion in androgen sensitive and castration-resistant prostate cancers." In Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-2704.

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Carter, Julia H., Reed Spaulding, James A. Deddens, Bruce M. Colligan, Grant Lewis, Jackson O. Pemberton, Jeremy R. Graff, and Larry E. Douglass. "Abstract A28: Eukaryotic initiation factor 4E phosphorylation in human malignant melanoma." In Abstracts: AACR Special Conference on Advances in Melanoma: From Biology to Therapy; September 20-23, 2014; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.mel2014-a28.

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Reports on the topic "Eukaryotic initiation factor eIF4GI"

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Fonseca, Bruno. Studying the Role of Eukaryotic Translation Initiation Factor 4E (eIF4E) Phosphorylation by MNK1/2 Kinases in Prostate Cancer Development and Progression. Fort Belvoir, VA: Defense Technical Information Center, June 2013. http://dx.doi.org/10.21236/ada612330.

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von Arnim, Albrecht G. Eukaryotic initiation factor 3 (eIF3) and 5’ mRNA leader sequences as agents of translational regulation in Arabidopsis. Final report. Office of Scientific and Technical Information (OSTI), February 2015. http://dx.doi.org/10.2172/1169186.

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Chamovitz, Daniel, and Albrecht Von Arnim. Translational regulation and light signal transduction in plants: the link between eIF3 and the COP9 signalosome. United States Department of Agriculture, November 2006. http://dx.doi.org/10.32747/2006.7696515.bard.

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The COP9 signalosome (CSN) is an eight-subunit protein complex that is highly conserved among eukaryotes. Genetic analysis of the signalosome in the plant model species Arabidopsis thaliana has shown that the signalosome is a repressor of light dependent seedling development as mutant Arabidopsis seedlings that lack this complex develop in complete darkness as if exposed to light. These mutant plants die following the seedling stage, even when exposed to light, indicating that the COP9 signalosome also has a central role in the regulation of normal photomorphogenic development. The biochemical mode of action of the signalosome and its position in eukaryotic cell signaling pathways is a matter of controversy and ongoing investigation, and recent results place the CSN at the juncture of kinase signaling pathways and ubiquitin-mediated protein degradation. We have shown that one of the many CSN functions may relate to the regulation of translation through the interaction of the CSN with its related complex, eukaryotic initiation factor (eIF3). While we have established a physical connection between eIF3 subunits and CSN subunits, the physiological and developmental significance of this interaction is still unknown. In an effort to understand the biochemical activity of the signalosome, and its role in regulating translation, we originally proposed to dissect the contribution of "h" subunit of eIF3 (eIF3h) along the following specific aims: (i) Isolation and phenotypic characterization of an Arabidopsis loss-of-function allele for eIF3h from insertional mutagenesis libraries; (ii) Creation of designed gain and loss of function alleles for eIF3h on the basis of its nucleocytoplasmic distribution and its yeast-two-hybrid interactions with other eIF3 and signalosome partner proteins; (iii) Determining the contribution of eIF3h and its interaction with the signalosome by expressing specific mutants of eIF3h in the eIF3h- loss-of function background. During the course of the research, these goals were modified to include examining the genetic interaction between csn and eif3h mutations. More importantly, we extended our effort toward the genetic analysis of mutations in the eIF3e subunit, which also interacts with the CSN. Through the course of this research program we have made several critical scientific discoveries, all concerned with the apparent diametrically opposed roles of eIF3h and eIF3e. We showed that: 1) While eIF3e is essential for growth and development, eIF3h is not essential for growth or basal translation; 2) While eIF3e has a negative role in translational regulation, eIF3h is positively required for efficient translation of transcripts with complex 5' UTR sequences; 3) Over-accumulation of eIF3e and loss-of-function of eIF3h both lead to cop phenotypes in dark-grown seedlings. These results were published in one publication (Kim et al., Plant Cell 2004) and in a second manuscript currently in revision for Embo J. Are results have led to a paradigm shift in translation research – eIF3 is now viewed in all systems as a dynamic entity that contains regulatory subuits that affect translational efficiency. In the long-term agronomic outlook, the proposed research has implications that may be far reaching. Many important plant processes, including developmental and physiological responses to light, abiotic stress, photosynthate, and hormones operate in part by modulating protein translation [23, 24, 40, 75]. Translational regulation is slowly coming of age as a mechanism for regulating foreign gene expression in plants, beginning with translational enhancers [84, 85] and more recently, coordinating the expression of multiple transgenes using internal ribosome entry sites. Our contribution to understanding the molecular mode of action of a protein complex as fundamental as eIF3 is likely to lead to advances that will be applicable in the foreseeable future.

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