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Han,Ching Tack,Moon,Sung Joon The Korea Science and Technology Center 1998 BMB Reports Vol.31 No.2
Amino acid analogs, like other inducers of stress response, induce the synthesis of stress proteins in mammalian cells. In this study, Drosophila Kc cells, in which translation is tightly controlled during stress response, was treated with proline analogs, L-azetidine-2-carboxylic acid (AzC) and 3,4-dehydro-Lproline (dh-P). kc cells exposed to Azc or dh-P induced the synthesis of several proteins which had the same molecual weights as known heat shock proteins. However, in Kc cells, normal protein synthesis still continued in the presence of amino acids analogs unlike in heat-shocked cells. For the induction of stress response, the incorporation of dh-P into the protein was not essential, but the incorporation of AzC was. The stress protein synthesis was regulated mainly at the transcriptional level by AzC, whereas it was regulated by dh-P at the transcription level and possibly post-transcription level. During recovery, the stress protein synthesis stopped sooner in analog-treated than in heat-shocked cells even though the accumulated amount of Hsp70 was much less in proline analogs-treated cells. It could be concluded that the proline analogs, AzC and dh-P,induced stress response through a different mechanism from heat shock.
Heat - Shocked Drosophila Kc Cells Have Differential Sensitivity to Translation Inhibitors
Han, Ching Tack 생화학분자생물학회 1982 BMB Reports Vol.30 No.1
The heat shock response is a universal stress response observed in all organisms and cultured cells. The response is regulated at both the transcriptional and translational level. Heat shocked Drosophila melanogaster Kc cells are used as the system for the study of translational regulation. In this system non-heat shock messages are associated with polysome but are not translated in a heat shocked condition. To figure out the change in the translation machinery, the effects of translation elongation inhibitors were tested on Kc cells. The result showed that the sensitivity of translation to these drugs changed in heat shocked cells. The significant changes were the decreased inhibition of heat shock protein synthesis by cycloheximide, emetine. and puromycin, and the increased inhibition of heat shock protein synthesis by verrucarin A. implying that the translation elongation mechanism in heat shocked cells changed.
Han, Ching Tack,Moon, Sung Joon 생화학분자생물학회 1999 BMB Reports Vol.31 No.2
Amino acid analogs, like other inducers of stress response, induce the synthesis of stress proteins in mammalian cells. In this study, Drosophild Kc cells, in which translation is tightly controlled during stress response, was treated with proline analogs, L-azetidine-2-carboxylic acid (AzC) and 3,4-dehydro-L-proline (dh-P). Kc cells exposed to AzC or dh-P induced the synthesis of several proteins which had the same molecular weights as known heat shock proteins. However, in Kc cells, normal protein synthesis still continued in the presence of amino acids analogs unlike in heat-shocked cells. For the induction of stress response, the incorporation of dh-P into the protein was not essential, but the incorporation of AzC was. The stress protein synthesis was regulated mainly at the transcriptional level by AzC, whereas it was regulated by dh-P at the transcription level and possibly post-transcription level. During recovery, the stress protein synthesis stopped sooner in analog-treated cells than in heat-shocked cells even though the accumulated amount of Hsp70 was much less in proline analogs-treated cells. It could be concluded that the proline analogs, AzC and dh-P, induced stress response through a different mechanism from heat shock.
Heat-Shocked Drosophila Kc Cells Have Differential Sensitivity to Translation Inhibitors
Han, Ching-Tack Korean Society for Biochemistry and Molecular Biol 1997 Journal of biochemistry and molecular biology Vol.30 No.1
The heat shock response is a universal stress response observed in all organisms and cultured cells. The response is regulated at both the transcriptional and translational level. Heat shocked Drosophila melanogaster Kc cells are used as the system for the study of translational regulation. In this system non-heat shock messages are associated with polysome but are not translated in a heat shocked condition. To figure out the change in the translation machinery. the effects of translation elongation inhibitors were tested on Kc cells. The result showed that the sensitivity of translation to these drugs changed in heat shocked cells. The significant changes were the decreased inhibition of heat shock protein synthesis by cycloheximide, emetine. and puromycin. and the increased inhibition of heat shock protein synthesis by verrucarin A. implying that the translation elongation mechanism in heat shocked cells changed.
초파리 세포에서의 EF - 1α 의 동정 및 특성에 관한 연구
한징택 한국유전학회 1996 Genes & Genomics Vol.18 No.1
EF-l α protein is identified and partially purified in Drosophila. EF-l α appeares as double bands of 49 and 51 KD on SDS-polyacrylamide gel. Both are basic proteins and bind to GTP as EF-1 α protein in other organisms. Polyclonal antibodies were prepared against both 49 kD and 51 kD protein in the rabbit. The antibodies crossreact with both Drosophila and yeast EF-1 α In Drosophila Kc cells it is shown that EF-1 α exists as heterogeneous forms of 49-400 KD in the physiological condition.
Expression Characteristics of Pokeweed Antiviral Proteins(PAPs) : Two Distinct Types of Proteins
Hur, Yoonkang,Han, Ching-Tack,Maeng, Jueson 충남대학교 생물공학연구소 1998 생물공학연구지 Vol.6 No.-
Pokeweed antiviral proteins (PAPs) become novel therapeutic agents in relation to application in human viral diseases and cancer, as well as potent tools in plant system for defending viral infection. We have studied the expression characteristics of PAAs in pokeweed plants by western blot analysis. PAP-Ⅰwas constitutively expressed in leaves, stems and roots of the pokeweed plant, while PAP-Ⅱ was not expressed in roots. The expression of PAP-Ⅱ began in May and then gradually increased with development of the plants. The PAP-Ⅱ expression was induced and/or stimulated not only by biotic stresses, such as insect pests and viral infection, but also by abiotic stresses, like drought. Interestingly, low-light intensity was found to be more effective than high-light in the expression of both PAP-Ⅰand PAP-Ⅱ. Our results suggest the PAP-Ⅱ appears to have an additive effect in terms of proteciton of the plant against pathogens during summer-time when the plant actively grows and is attacked by various pathogens.
Production of Pokeweed Antiviral Proteins Nontoxic to Cells by Mutagenesis of PAP-cDNA
Hur, Yoonkang,Han, Ching-Tack,Park, Sangkyu 충남대학교 생물공학연구소 1999 생물공학연구지 Vol.7 No.-
Pokeweed antiviral protein (PAP), one of ribosome inactivating proteins (RIPs), has very strong toxicity both to prokaryotic and eukaryotic cells. To produce mutant PAPs nontoxic to cells, the PAP-cDNA was inserted into a yeast-E. coli shuttle vector under the control of galactose promoter, mutagenized using hydroxylamine, and transformed into yeast cells. Transformed yeast cells were selected on the uracil-deficient plate containing glucose or raffinose, and the yeast cells producing mutant PAPs nontoxic to cells were then selected on the galactose plate. Eighteen mutants were obtained by immunoblot analyses of 1,000 transformants: among them, three, ten and five mutants among them did not inhibit the yeast cell growth, and showed no or less inhibition of protein synthesis in vitro. Six among fourteen mutants were able to protect TMV infection in coinoculation experiment. The mutant PAPs showing an antiviral activity either without or reduced RIP activity contain neither the active site mutation nor C-terminal deletion mutation. These results suggest that both the RIP activity and the antiviral activity will require other amino acid residue(s) besides the active site and that the antiviral acitivity of PAP can be dissociated from its toxicity.
Lee, Jeong-Yeo,Han, Ching-Tack,Hur, Yoon-Kang Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.29 No.2
Proteins that contain membrane occupation and recognition nexus (MORN) motifs regulate various aspects of cellular metabolism by localizing proteins in different cellular organelles. The full-length Brassica rapa MORN motif protein (BrMORN) cDNA consists of 1,510 bp encoding 502 deduced amino acids with a predicted molecular mass of 55.8 kDa and an isoelectric point of 9.72. BrMORN is a novel protein composed of two N-terminal transmembrane helices and seven C-terminal MORN motifs and it appears to be localized on the plastid envelope. BrMORN expression was relatively high in actively-growing tissues, but low in mature tissues and under some abiotic stresses. Arabidopsis thaliana plants overexpressing BrMORN showed an enhanced rate of growth, hypocotyl elongation, and increases in the size of vegetative organs and seed productivity under normal growth conditions. In addition, cell size in Arabidopsis plants overexpressing BrMORN was 24% larger than that of wild-type plants, implying that the increase in the size of vegetative organs is due to cell enlargement. The increased size of the vegetative organs also led to increased seed production. Our data suggest that the MORN motif of BrMORN may act at the plastid envelope and facilitate plant growth via cell enlargement.