Phosphorylation of elongation factor 1 and ribosomal protein S6 by multipotential S6 kinase and insulin stimulation of translational elongation

Stimulation of protein synthesis in response to insulin is concomitant with increased phosphorylation of initiation factors 4B and 4G and ribosomal protein S6 (Morley, S. J., and Traugh, J. A. (1993) Biochimie 75, 985-989) and is due at least in part to multipotential S6 kinase. When elongation factor 1 (EF-1) from rabbit reticulocytes was examined as substrate for multipotential S6 kinase, up to 1 mol/mol of phosphate was incorporated into the alpha, beta, and delta subunits. Phosphorylation of EF-1 resulted in a 2-2. 6-fold stimulation of EF-1 activity, as measured by poly(U)-directed polyphenylalanine synthesis. The rate of elongation was also stimulated by approximately 2-fold with 80 S ribosomes phosphorylated on S6 by multipotential S6 kinase. When the rates of elongation in extracts from serum-fed 3T3-L1 cells and cells serum-deprived for 1.5 h were compared, a 40% decrease was observed upon serum deprivation. The addition of insulin to serum-deprived cells for 15 min stimulated elongation to a rate equivalent to that of serum-fed cells. Similar results were obtained with partially purified EF-1, with both EF-1 and ribosomes contributing to stimulation of elongation. These data are consistent with a ribosomal transit time of 3.2 min for serum-deprived cells and 1.6 min following the addition of insulin for 15 min. Taken together, the data suggest that insulin stimulation involves coordinate regulation of EF-1 and ribosomes through phosphorylation by multipotential S6 kinase.     

X-Ray Diffraction Study of Ba6-3x (Eu1/2 Nd1/2)8+2x Ti18O54 Microwave Dielectric Ceramics Prepared by Sol-Gel Method

Perfectly-sintered Ba_6-3x (Eu_1/2 Nd_1/2)_8+2x Ti₁₈O₅₄ (x = 2/3) (BENT) microwave dielectric ceramics was fabricated successfully with BENT powders prepared by Sol-Gel process. The lattice parameters of BENT ceramic powders were determined by method of X-ray diffraction in ordinary temperature. Orthorhombic lattice type (space group Pbam) of BENT in ordinary temperature was determined, its pattern was indexed and its polycrystalline X-ray diffraction data were listed. By analysis of its X-ray diffraction data, it could be concluded that Eu and Nd coexisted in the single phase and could not be distinguished in BENT ceramics. The increasing dielectric losses of BENT could be explained basically by the disorder of Eu ions and Nd ions occupied in Al-sites.     

Study on UV Excitation Properties of Eu^3＋ at S6 Site in Bulk and Nanocrystalline Cubic Y2O3

Increases of emission intensities for Eu^3 at the S6 site relative to that at the C2 site were observed as UV excitation wavelength decreases from 300 nm to 200 nm in both bulk and nanocrystalline cubic Y2O3:Eu^3 . Decomposition of excitation spectra shows that the charge transfer band of Eu^3 at the S6 site lies in the high-energy side of that at the C2 site, resulting in that the energy transfer from the host prefers to the S6 site. Detailed emission and excitation spectral characteristics were analyzed and discussed. In addition, spectral red-shift were found in both charge transfer bands in nanocrystalline Y2O3: Eu^3 compared to the bulk material. The number ratio of S6 sites to C2 sites is also smaller in nanocrystalline Y2O3:Eu^3 than that in the bulk one.     

RAFT1 phosphorylation of the translational regulators p70 S6 kinase and 4E-BP1

The complex of rapamycin with its intracellular receptor, FKBP12, interacts with RAFT1/FRAP/mTOR, the in vivo rapamycin-sensitive target and a member of the ataxia telangiectasia mutated (ATM)-related family of kinases that share homology with the catalytic domain of phosphatidylinositol 3-kinase. The function of RAFT1 in the rapamycin-sensitive pathway and its connection to downstream components of the pathway, such as p70 S6 kinase and 4E-BP1, are poorly understood. Here, we show that RAFT1 directly phosphorylates p70(S6k), 4E-BP1, and 4E-BP2 and that serum stimulates RAFT1 kinase activity with kinetics similar to those of p70(S6k) and 4E-BP1 phosphorylation. RAFT1 phosphorylates p70(S6k) on Thr-389, a residue whose phosphorylation is rapamycin-sensitive in vivo and necessary for S6 kinase activity. RAFT1 phosphorylation of 4E-BP1 on Thr-36 and Thr-45 blocks its association with the cap-binding protein, eIF-4E, in vitro, and phosphorylation of Thr-45 seems to be the major regulator of the 4E-BP1-eIF-4E interaction in vivo. RAFT1 phosphorylates p70(S6k) much more effectively than 4E-BP1, and the phosphorylation sites on the two proteins show little homology. This raises the possibility that, in vivo, an unidentified kinase analogous to p70(S6k) is activated by RAFT1 phosphorylation and acts at the rapamycin-sensitive phosphorylation sites of 4E-BP1.     

Luminescent Properties of Ca2 Y8 ( SiO4 ) 6O2:Eu3 + Phosphors Prepared by Spray Pyrolysis Process

Using CaCO3, metal oxides (all dissolved by nitric acid) and tetraethoxysilane Si (OC2H5 )4 (TEOS) as the main starting materials, Ca2Y8 (SiO4 )6O2: Eu3 phosphors were synthesized by spray pyrolysis.X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting phosphors.The results of XRD indicated that the 1000 ℃ annealed powders crystallize with the silicate oxyapatite structure.SEM study revealed that the phosphors consist of spherical particles with an average size of about 1 ～ 3 μm.In the crystalline Ca2 Y8 (SiO4)6O2: Eu3 phosphor, the Eu3 shows its characteristic emission corresponding to 5 D0 - 7 FJ ( J = 0, 1,2, 3, 4) transitions, with 5D0 - 7 F2 red emission (613 nm) as the most prominent group, agreeing well with the structure of the host material.     

Crystal Structure and Spectra of the Complex Eu(p-ClC_6H_4COO)_3C_(12)H_8N_2

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅａｎｄＳｐｅｃｔｒａｏｆｔｈｅＣｏｍｐｌｅｘＥｕ（ｐ－ＣｌＣ_６Ｈ_４ＣＯＯ）_３Ｃ_（１２）Ｈ_８Ｎ_２ＪｉｎＬｉｎｐｅｉ（金林培）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＢｅｉｊｉｎｇＮｏｒｍａｌＵｎｉｖｅｒｓｉｔ...     

Immunohistochemical localization of S100A1 and S100A6 in postnatally developing salivary glands of rats

S100 proteins are calcium-binding proteins of the EF-hand superfamily and are involved in the regulation of a number of cellular processes. The present study deals with the immunohistochemical expression of S100A1 and S10100A6 in the rat submandibular and sublingual glands during postnatal development from day 0 to 12 weeks. Expression of S100A1 was particularly concentrated in pillar and transition cells in the granular convoluted tubule (GCT) and in striated duct cells of the submandibular gland age 4 weeks to maturity. None or only weak staining for S100A1 was observed in the duct segment at 0-5 days. On the contrary, immunostaining of S100A6 was present in proacinar cells in undifferentiated submandibular gland at age 3 days to 2 weeks. S100A6 immunoreactivity in rat submandibular gland coexisted with chromogranin reactivity. It is possible that S100A6 regulates secretion of chromogranin in proacinar cells. Secretion of growth factors and biologically active peptides in the GCT are regulated by calcium signals, and S100A1 may be involved in the secretory mechanism of granular cells. S100A1 and S100A6 are potentially of great importance in secretory functions of granular cells and proacinar cells, as well as in rat salivary glands.