Disease relevance of Eef2

• The ability of GA to inhibit the growth of glioma cells was abrogated by overexpressing EF-2 kinase [1].
• Disruption of the EF-2 kinase/Hsp90 protein complex: a possible mechanism to inhibit glioblastoma by geldanamycin [1].
• Myocardial ischemia and increased heart work modulate the phosphorylation state of eukaryotic elongation factor-2 [2].
• To address potential regulation of the elongation step by changes in eukaryotic elongation factor 2 (eEF2) phosphorylation with and without acquired ischemic tolerance (IT), Wistar rats were preconditioned by 5-min sublethal ischemia and 2 days later, 30-min lethal ischemia was induced [3].
• Muscle atrophy appears to be caused by changes in mRNA levels of specific regulators of proteolysis, protein synthesis, and contractile apparatus assembling, such as polyubiquitin, elongation factor 2, and nebulin [4].

High impact information on Eef2

• The carboxyl-terminal half of EF-2 contains several regions that have 34-75% homology with bacterial elongation factor G. These results suggest that the amino-terminal region of EF-2 participates in the GTP-binding and GTPase activity whereas the carboxyl-terminal region interacts with ribosomes [5].
• Comparative studies of sequence homology among EF-2 and several GTP-binding proteins show that five regions in the amino-terminal position of EF-2, corresponding to about 160 amino acids, show homology with GTP-binding proteins, including protein synthesis elongation and initiation factors, mammalian ras proteins, and transducin [5].
• Amino acid sequence of mammalian elongation factor 2 deduced from the cDNA sequence: homology with GTP-binding proteins [5].
• It has been shown that AMPK activation is associated with inhibition of protein synthesis via phosphorylation of elongation factor 2 (eEF2) in cardiomyocytes [6].
• Treatment of cell lines for 24-48 h of GA or 17-AAG disrupted EF-2-kinase/Hsp90 interactions as measured by coimmunoprecipitation, resulting in a decreased amount of recoverable kinase in cell lysates [1].

Chemical compound and disease context of Eef2

• Previously, we have shown that CaM-dependent protein kinase III phosphorylates elongation factor 2 (EF-2) in proliferating, C6 glioma cells but not in normal white matter, a tissue rich in nonproliferating glia [7].
• Pseudomonas exotoxin A inhibits peptide chain elongation by ADP-ribosylating elongation factor 2 [8].
• Phosphorylation of EF-2 was increased by preganglionic stimulation or by treatment of the ganglion with dimethylphenylpiperazinium or veratridine [9].

Biological context of Eef2

• The expression of EF-2 or alpha4, but not the Cdc-like protein, was dependent on cell densities [10].
• These results suggest that intracellular Ca2+ inhibits protein synthesis in mammalian cells via CaM-dependent protein kinase III-catalyzed phosphorylation of EF-2 [11].
• EF-2 cDNA clones were isolated from gradually constructed small (1000-5000 clones) specific cDNA libraries using the primer extension method for synthesis of the first cDNA chain [12].
• Comparison of this cDNA with hamster cDNA has shown that (i) the base sequences had a 89.7% homology while that of the 5'-untranslated region was 73%; (ii) there are two amino acid replacement in rat liver EF-2 as compared with hamster EF-2 [12].
• Functional characterization of the promoter region of the chicken elongation factor-2 gene [13].

Anatomical context of Eef2

• Eukaryotic EF2 phosphorylated levels were notably low only in the cortex, whereas levels in the hippocampus were close to that of sham controls [3].
• 8-bromo-cAMP increased chicken EF-2 promoter activity (-700/+102) in Rat 1 HIR fibroblast cells more than insulin and phorbol ester treatment [13].
• Phosphorylation of elongation factor 2 in normal and malignant rat glial cells [14].
• Purification and properties of rabbit reticulocyte protein synthesis elongation factor 2 [15].
• Under these conditions it is likely that enough toxin is able to bypass the block in toxin-specific entry and reach the cytosol by a second, less efficient, nonspecific mechanism to catalyze the inactivation of elongation factor 2 and inhibit protein synthesis [16].

Associations of Eef2 with chemical compounds

• In parallel with the effects on EF-2 dephosphorylation, addition of high glucose to 832/13 cells markedly increased the incorporation of [(35)S]methionine into total protein [17].
• Dephospho-EF-2 could support poly(U)-directed polyphenylalanine synthesis in a reconstituted elongation system when combined with EF-1 [11].
• Amino acid sequencing of the purified tryptic phosphopeptide revealed that this threonine residue lies within the sequence: Ala-Gly-Glu-Thr-Arg-Phe-Thr-Asp-Thr-Arg (residues 51-60 of EF-2) [11].
• Accordingly, glucose-mediated dephosphorylation of EF-2 was completely blocked by the mitochondrial respiratory antagonists antimycin A and oligomycin [17].
• Addition of 5-aminoimidazole-4-carboxamide 1-beta-d-ribofuranoside in high glucose led to a marked stimulation of EF-2 phosphorylation, consistent with the possibility that increased AMP kinase activity in low glucose stimulates EF-2 kinase [17].

Regulatory relationships of Eef2

• EF-2 regulates protein synthesis while the alpha4 and Cdc5-like phosphoproteins have been implicated in IgG receptor-mediated and mitogen-activated signaling, respectively [10].

Other interactions of Eef2

• The complete primary structure of cDNA and protein EF-2 from rat liver was derived taking into account the primary structure of the 3'-terminal region EF-2 cDNA previously reported [(1986) Proc. Natl. Acad. Sci. USA 83, 4978-4982] [12].
• Protein phosphatase-2A activity was stimulated by glucose addition to 832/13 cells, but neither protein phosphatase-1 nor calmodulin kinase III (EF-2 kinase) activity was affected under these conditions [17].
• At the same time these secretagogues reduced elongation factor 2 (eEF2) phosphorylation, the main factor known to regulate elongation, and increased the phosphorylation of the eEF2 kinase [18].
• Instead, blockade of calcineurin with FK506 reduced the phosphorylation of the eIF4E binding protein, reduced the formation of the eIF4F complex, and increased the phosphorylation of eukaryotic elongation factor 2 [19].
• We demonstrated that both hindlimb unloading and denervation produce alterations in the phosphorylation and/or total amount of the 70-kDa ribosomal S6 kinase, eukaryotic initiation factor 2 alpha-subunit, and eukaryotic elongation factor 2 [20].

Analytical, diagnostic and therapeutic context of Eef2

• EF-2, purified 1,960-fold, appears to be active as a single polypeptide chain with a molecular weight of approximately 100,000 based upon the following determinations: sodium dodecyl sulfate gel electrophoresis (95,000); sedimentation equilibrium centrifugation (112,000); gel filtration (97,000); ADP-ribosylation (103,000) [15].
• However, by analyzing the incubation mixtures by thin layer chromatography the fraction of the total nucleotide binding to EF-2 which was due to GDP could be determined and corrected for [21].
• Samples of unmodified EF-2, EF-2 ADP-ribosylated with diphtheria toxin and NAD, and/or phosphorylated using ATP and the Ca(2+)-calmodulin dependent kinase III partially purified, were irradiated at 254 nm with 32P-labeled GDP or GTP, and analyzed by one- and two-dimensional gel electrophoresis [22].
• However, density gradient centrifugation of the cross-linked ribosomal complexes showed an increased density (1.25 g/cm3) of the factor, as expected from a covalent complex between EF-2 and a low-molecular-weight RNA species [23].
• We have examined by immunoblotting the effect of three oxidant compounds on the level of hepatic elongation factor-2 (eEF-2) [24].

References