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51.
Insulin-induced GLUT4 translocation involves protein kinase C-lambda-mediated functional coupling between Rab4 and the motor protein kinesin 总被引:1,自引:0,他引:1 下载免费PDF全文
Imamura T Huang J Usui I Satoh H Bever J Olefsky JM 《Molecular and cellular biology》2003,23(14):4892-4900
Insulin stimulates glucose transport by promoting translocation of GLUT4 proteins from the perinuclear compartment to the cell surface. It has been previously suggested that the microtubule-associated motor protein kinesin, which transports cargo toward the plus end of microtubules, plays a role in translocating GLUT4 vesicles to the cell surface. In this study, we investigated the role of Rab4, a small GTPase-binding protein, and the motor protein KIF3 (kinesin II in mice) in insulin-induced GLUT4 exocytosis in 3T3-L1 adipocytes. Photoaffinity labeling of Rab4 with [gamma-(32)P]GTP-azidoanilide showed that insulin stimulated Rab4 GTP loading and that this insulin effect was inhibited by pretreatment with the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY294002 or expression of dominant-negative protein kinase C-lambda (PKC-lambda). Consistent with previous reports, expression of dominant-negative Rab4 (N121I) decreased insulin-induced GLUT4 translocation by 45%. Microinjection of an anti-KIF3 antibody into 3T3-L1 adipocytes decreased insulin-induced GLUT4 exocytosis by 65% but had no effect on endocytosis. Coimmunoprecipitation experiments showed that Rab4, but not Rab5, physically associated with KIF3, and this was confirmed by showing in vitro association using glutathione S-transferase-Rab4. A microtubule capture assay demonstrated that insulin stimulation increased the activity for the binding of KIF3 to microtubules and that this activation was inhibited by pretreatment with the PI3-kinase inhibitor LY294002 or expression of dominant-negative PKC-lambda. Taken together, these data indicate that (i) insulin signaling stimulates Rab4 activity, the association of Rab4 with kinesin, and the interaction of KIF3 with microtubules and (ii) this process is mediated by insulin-induced PI3-kinase-dependent PKC-lambda activation and participates in GLUT4 exocytosis in 3T3-L1 adipocytes. 相似文献
52.
Y box-binding protein-1 binds preferentially to single-stranded nucleic acids and exhibits 3'-->5' exonuclease activity 下载免费PDF全文
Izumi H Imamura T Nagatani G Ise T Murakami T Uramoto H Torigoe T Ishiguchi H Yoshida Y Nomoto M Okamoto T Uchiumi T Kuwano M Funa K Kohno K 《Nucleic acids research》2001,29(5):1200-1207
We have previously shown that Y box-binding protein-1 (YB-1) binds preferentially to cisplatin-modified Y box sequences. Based on structural and biochemical data, we predicted that this protein binds single-stranded nucleic acids. In the present study we confirmed the prediction and also discovered some unexpected functional features of YB-1. We found that the cold shock domain of the protein is necessary but not sufficient for double-stranded DNA binding while the C-tail domain interacts with both single-stranded DNA and RNA independently of the cold shock domain. In an in vitro translation system the C-tail domain of the protein inhibited translation but the cold shock domain did not. Both in vitro pull-down and in vivo co-immunoprecipitation assays revealed that YB-1 can form a homodimer. Deletion analysis mapped the C-tail domain of the protein as the region of homodimerization. We also characterized an intrinsic 3′→5′ DNA exonuclease activity of the protein. The region between residues 51 and 205 of its 324-amino acid extent is required for full exonuclease activity. Our findings suggest that YB-1 functions in regulating DNA/RNA transactions and that these actions involve different domains. 相似文献
53.
Suzuki T Sakurai K Imamura A Nakamura A Ueguchi C Mizuno T 《Bioscience, biotechnology, and biochemistry》2000,64(11):2486-2489
Histidine (His)-to-Aspartate (Asp) phosphorelay signal transduction systems are generally made up of a "sensor histidine (His)-kinase", a "response regulator", and a "histidine-containing phosphotransmitter (HPt)". In the higher plant, Arabidopsis thaliana, results from recent intensive studies suggested that the His-to-Asp phosphorelay mechanism is at least partly responsible for propagation of environmental stimuli, such as phytohormones (e.g. ethylene and cytokinin). Here we compiled the members of the HPt family of phosphotransmitters in Arabidopsis thaliana (AHP-series, Arabidopsis HPt phosphotransmitters), based on both database and experimental analyses, in order to provide a comprehensive basis at the molecular level for understanding the function of the AHP phosphotransmitters that are implicated in the His-to-Asp phosphorelay of higher plants. 相似文献
54.
Imamura N Ishikawa T Ohtsuka T Yamamoto K Dekura M Fukami H Nishida R 《Bioscience, biotechnology, and biochemistry》2000,64(10):2216-2217
An antibiotic-producing Penicillium sp. strain was isolated from cocoons of the leaf-rolling moth, Dactylioglypha tonica. An antibacterial compound was isolated from the cultured broth, and the chemical structure of the principle was determined by spectroscopic data to be a derivative of isocoumarincarboxylate. 相似文献
55.
56.
Imamura H Ohtake N Shimizu A Sato H Sugimoto Y Sakuraba S Kiyonaga H Suzuki-Sato C Nakano M Nagano R Yamada K Hashizume T Morishima H 《Bioorganic & medicinal chemistry letters》2000,10(2):115-118
Through further derivatization of J-111,347 (1a), a trans-3,5-disubstituted pyrrolidinylthio-1beta-methylcarbapenem, undesired epileptogenicity in a rat intracerebroventricular assay (200 microg/rat) could be eliminated to afford J-111,225 (2a), J-114,870 (3a) and J-114,871 (3b) which preserved comparable broad antimicrobial activity. 相似文献
57.
Takamatsu H Imamura A Kodama T Asai K Ogasawara N Watabe K 《FEMS microbiology letters》2000,192(1):33-38
The synthesis and proteolysis of the spore coat proteins, SpoIVA and YrbA, of Bacillus subtilis were analyzed using antisera. Almost no intact full-length proteins of either type were extracted from wild-type spores, while yabG mutant spores contained intact SpoIVA and YrbA proteins. We purified recombinant YrbA and YabG proteins from Escherichia coli transformants and found that YrbA was cleaved to the smaller moiety in the presence of YabG in vitro. These observations indicate that YabG is a protease involved in the proteolysis and maturation of SpoIVA and YrbA proteins, conserved with the cortex and/or coat assembly by B. subtilis. 相似文献
58.
59.
Ito M Ito R Huang Y Miura S Imamura A Suzuki Y Shimozawa N 《Biochimica et biophysica acta》2000,1496(2-3):232-242
We isolated and characterized CHO mutants deficient in peroxisome assembly using green fluorescent protein (GFP) and blue fluorescent protein (BFP) as the fluorescent probes to study the molecular mechanism of peroxisome biogenesis. We used stable transformants of CHO cells expressing GFP appending peroxisome targeting signal-1 (PTS1) and/or peroxisome targeting signal-2 (PTS2) as the parent strains for rapid isolation of the mutants. We have obtained six peroxisome-deficient mutants by visual screening of the mislocalizations of the peroxisomal GFPs. Mutual cell fusion experiments indicated that the six mutants isolated were divided into four complementation groups. Several of the mutants obtained possessed defective genes: the PEX2 gene was defective in SK24 and PT54; the PEX5 gene in SK32 and the PEX7 gene in PT13 and PT32. BE41, which belonged to the fourth complementation group, was not determined. When peroxisomal forms of BFP were transiently expressed in mutant cells, the peroxisomal BFPs appending both PTS1 and PTS2 appeared to bypass either the PTS1 or PTS2 pathway for localization in SK32. This observation suggested that other important machinery, in addition to the PTS1 or PTS2 pathway, could be involved in peroxisome biogenesis. Thus, our approach using peroxisomal fluorescent proteins could facilitate the isolation and analysis of peroxisome-deficient CHO mutants and benefit studies on the identification and role of the genes responsible for peroxisome biogenesis. 相似文献
60.
Rho and Rab Small G Proteins Coordinately Reorganize Stress Fibers and Focal Adhesions in MDCK Cells 总被引:6,自引:1,他引:5 下载免费PDF全文
Hiroshi Imamura Kenji Takaishi Katsutoshi Nakano Atsuko Kodama Hideto Oishi Hitoshi Shiozaki Morito Monden Takuya Sasaki Yoshimi Takai 《Molecular biology of the cell》1998,9(9):2561-2575
The Rho subfamily of the Rho small G protein family (Rho) regulates formation of stress fibers and focal adhesions in many types of cultured cells. In moving cells, dynamic and coordinate disassembly and reassembly of stress fibers and focal adhesions are observed, but the precise mechanisms in the regulation of these processes are poorly understood. We previously showed that 12-O-tetradecanoylphorbol-13-acetate (TPA) first induced disassembly of stress fibers and focal adhesions followed by their reassembly in MDCK cells. The reassembled stress fibers showed radial-like morphology that was apparently different from the original. We analyzed here the mechanisms of these TPA-induced processes. Rho inactivation and activation were necessary for the TPA-induced disassembly and reassembly, respectively, of stress fibers and focal adhesions. Both inactivation and activation of the Rac subfamily of the Rho family (Rac) inhibited the TPA-induced reassembly of stress fibers and focal adhesions but not their TPA-induced disassembly. Moreover, microinjection or transient expression of Rab GDI, a regulator of all the Rab small G protein family members, inhibited the TPA-induced reassembly of stress fibers and focal adhesions but not their TPA-induced disassembly, indicating that, furthermore, activation of some Rab family members is necessary for their TPA-induced reassembly. Of the Rab family members, at least Rab5 activation was necessary for the TPA-induced reassembly of stress fibers and focal adhesions. The TPA-induced, small G protein-mediated reorganization of stress fibers and focal adhesions was closely related to the TPA-induced cell motility. These results indicate that the Rho and Rab family members coordinately regulate the TPA-induced reorganization of stress fibers and focal adhesions that may cause cell motility. 相似文献