• 대한약리학회지
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• 제31권2호
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• pp.241-250
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• 1995

Protein B23 is one of the major nucleolar phosphoproteins associated with pre-ribosomal particles, and is localized in the granular region of the nucleolus. Recent studies suggest that protein B23 shuttles between nucleus and cytoplasm and also interacts with HIV Rev. These findings indicate that protein B23 is important in nucleocytoplasmic relationship and viral replication. However, the exact function of protein B23 is not clear yet. In acute nucleolar hypertrophy of rat liver, treated with thioacetamide, there was observed an increase of not only protein B23 but also B23-like protein p45 when anti-B23 monoclonal antibody (MAb) was used for identification. On the basis of the large B23 specific epitope structure composed of 68 amino acids, a hypothesis was formulated to examine that p45 is the pre-B23 resulting from excessive production of B23. In an attempt to investigate the precursor of B23, we analyzed the subcellular fractions and microsomal subfractions. Subsequently, we analyzed the finger printings of B23-like proteins using the tryptic peptide mapping. The results are summarized: 1) Using B23 MAb, we observed the presence of B23-like proteins in nucleolar fraction, nucleoplasmic fraction and microsomal fraction. 2) In the further microsomal subfractionation, we could partially purify B23-like protein in 2M layer of sucrose gradient. 3) When ion exchange chromatography was employed, there were protein species 80kDa(p80), 65kDa(p65) and 60kDa(p60). 4) Based on the tryptic map analysis of $^{125}I$ labeled proteins, the similarity between B23 and p80 was found only in 9 out of 14(B23) and 21(p80) peptides, and difference was found in the remaining peptides. p80 and p60 had 18 common peptides, and all the peptides of p60 were similar to those of p80. From these results, it is proposed that p45 is an abnormal metabolite resulting from carcinogenesis by thioacetamide, and it is not the precursor of B23. In addition, we suggest that p80 may be a precursor of p45.

• The Korean Journal of Physiology and Pharmacology
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• 제18권2호
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• pp.155-161
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• 2014

Overexpression of amyloid precursor protein with the Swedish mutation causes abnormal hyperphosphorylation of the microtubule-associated protein tau. Hyperphosphorylated isoforms of tau are major components of neurofibrillary tangles, which are histopathological hallmarks of Alzheimer's disease. Protein phosphatase 2A (PP2A), a major tau protein phosphatase, consists of a structural A subunit, catalytic C subunit, and a variety of regulatory B subunits. The B subunits have been reported to modulate function of the PP2A holoenzyme by regulating substrate binding, enzyme activity, and subcellular localization. In the current study, we characterized regulatory B subunit-specific regulation of tau protein phosphorylation. We showed that the PP2A B subunit PPP2R2A mediated dephosphorylation of tau protein at Ser-199, Ser-202/Thr-205, Thr-231, Ser-262, and Ser-422. Down-regulation of PPP2R5D expression decreased tau phosphorylation at Ser-202/Thr-205, Thr-231, and Ser-422, which indicates activation of the tau kinase glycogen synthase kinase 3 beta ($GSK3{\beta}$) by PP2A with PPP2R5D subunit. The level of activating phosphorylation of the $GSK3{\beta}$ kinase Akt at Thr-308 and Ser-473 were both increased by PPP2R5D knockdown. We also characterized B subunit-specific phosphorylation sites in tau using mass spectrometric analysis. Liquid chromatography-mass spectrometry revealed that the phosphorylation status of the tau protein may be affected by PP2A, depending on the specific B subunits. These studies further our understanding of the function of various B subunits in mediating site-specific regulation of tau protein phosphorylation.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.1010-1014
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• 2007

M1 RNA is the catalytic component of RNase P, a tRNA-processing enzyme in Escherichia coli. M1 RNA is produced in the cell by transcription of the rnpB gene and subsequent processing at the 3' end. The 3' flanking region of rnpB contains repeated sets of overlapping sequences coding for small proteins. The issue of whether these proteins are expressed remains to be established. In this study, we showed the expression of a small protein encoded by the first repeat within the 3' flanking region of rnpB. Interestingly, protein expression was increased at lower temperatures. The termination efficiency of rnpB terminators was decreased at lower temperatures, suggesting that antitermination is responsible for enhanced protein expression. Moreover, the purified small protein contained M1 RNA, implying a role as a specific RNA-binding protein.

• BMB Reports
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• 제33권1호
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• pp.59-62
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• 2000

Hepatitis C virus (HCV) nonstructural 5B (NS5B) protein is an RNA-dependent RNA polymerase (RdRp). To determine whether it can contribute to viral replication by interaction with cellular proteins, the yeast two-hybrid screening system was employed to screen a human liver cDNA library. Using the HCV NS5B as a bait, we have isolated positive clones encoding a cellular protein. The NS5B interacting protein, 5BIP, is a novel cellular protein of 170 amino acids. Interaction of the HCV NS5B protein with 5BIP was confirmed by a protein-protein blotting assay. Recently, we have demonstrated that NS5B possesses an RdRp activity and thus it is possible that 5BIP, in association with NS5B, plays a role in HCV replication.

• Biomolecules & Therapeutics
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• 제11권3호
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• pp.157-162
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• 2003

The generation of secretory IgA antibodies(Abs) for specific immune protection of mucosal surfaces depends on stimulation of the mucosal immune system, but this is not effectively achieved by parenteral or even oral administration of most soluble antigens. Thus, to produce a possible vaccine antigen against urinary tract infections, the uropathogenic E. coli (UPEC) adhesin was genetically coupled to the ctxa2b gene and cloned into a pMAL-p2E expression vector. The chimeric construction of pMALfimHIctxa2b was then transformed into E. coli K-12 TB1 and its nucleotide sequence was verified. The chimeric protein was then purified by applying the affinity chromatography. The purified chimeric protein was confirmed by SDS-PAGE and western blotting using antibodies to the maltose binding protein (MBP) or the cholera toxin subunit B (CTXB), plus the N-terminal amino acid sequence was analyzed. The orderly-assembled chimeric protein was confirmed by a modified $G_{M1}$-ganglioside ELISA using antibodies to adhesin. The results indicate that the purified chimeric protein was an Adhesin/CTXA2B protein containing UPEC adhesin and the $G_{M1}$-ganglioside binding activity of CTXB. This study also demonstrate that peroral administration of this chimeric immunogen in mice elicited high level of secretory IgA and serum IgG Abs to the UPEC adhesin. The results suggest that the genetically linked CTXA2B acts as a useful mucosal adjuvant, and that the adhesin/CTXA2B chimeric protein might be a potential antigen for oral immunization against UPEC.

• 생약학회지
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• 제41권3호
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• pp.227-231
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• 2010

Protein tyrosine phosphatase 1B (PTP1B) is predicted to be therapeutic target in treatment of type 2 diabetes and obesity. Thus, in order to search for PTP1B inhibitors, we screened the inhibitory activity of PTP1B in the water extracts of 84 medicinal herbs. Among them, the extracts of Pini Folium, Magnoliae Cortex, Artemisiae asiaticae Herba, Schizonepetae Herba, Menthae Herba, Mume Fructus, Cimicifugae Rhizoma, and Amomi Cardamomi Fructus showed relatively significant (58-68%) inhibitory activity against PTP1B. Especially, the methylene chloride fraction of the methanol extract of Menthae Herba (81% inhibition at 30 ${\mu}g$/ml) showed more potent inhibitory activity against PTP1B than others.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2000년도 추계학술발표대회
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• pp.15-23
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• 2000

The subcellular localization of the SopB protein, which is encoded by the Escherichia coli F plasmid and is involved in the partition of the single-copy plasmid, was directly visualized through the expression of the protein fused to the jellyfish green fluorescent protein (GFP). The fusion protein was found to localize to positions close but not at the poles of exponentially growing cells. Examination of derivatives of the fusion protein lacking various regions of SopB suggests that the signal for the cellular localization of SopB resides in a region close to its N terminus. Overexpression of SopB led to silencing of genes linked to, but well-separated from, a cluster of SopB-binding sites termed sopC. In this SopB-mediated repression of sopC-linked genes, all but the N-terminal 82 amino acids of SopB can be replaced by the DNA-binding domain of a sequence-specific DNA -binding protein, provided that the sopC locus is also replaced by the recognition sequence of the DNA-binding domain. These results suggest a mechanism of gene silencing: patches of closely packed DNA-binding protein is localized to specific cellular sites; such a patch can capture a DNA carrying the recognition site of the DNA -binding domain and sequestrate genes adjacent to the recognition site through nonspecific binding of DNA.

• Biomolecules & Therapeutics
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• 제13권2호
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• pp.101-106
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• 2005

The generation of secretory IgA antibodies (Abs) for specific immune protection of mucosal surfaces depends on stimulation of the mucosal immune system, but this is not effectively achieved by parenteral or even oral administration of most soluble antigens. Thus, to produce a possible vaccine antigen against urinary tract infections, the uropathogenic E. coli (UPEC) adhesin was genetically coupled to the heat-labile Escherichia coli enterotoxin A2B (ltxa2b) gene and cloned into a pMAL-p2E expression vector. The chimeric construction of pMALfimH/ltxa2b was then transformed into E. coli K-12 TB1 and its nucleotide sequence was verified. The chimeric protein was then purified by applying the affinity chromatography. The purified chimeric protein was confirmed by SDS-PAGE and westem blotting using antibodies to the maltose binding protein (MBP) or the heat labile E. coli subunit B (LTXB), plus the N-terminal amino acid sequence was analyzedd. The orderly-assembled chimeric protein was confirmed by a modified $G_{M1}$-ganglioside ELISA using antibodies to adhesin. The results indicate that the purified chimeric protein was an Adhesin/LTXA2B protein containing UPEC adhesin and the $G_{M1}$-ganglioside binding activity of LTXB. thisstudy also demonstrate that peroral administration of this chimeric immunogen in mice elicited high level of secretory IgA (sIgA) and serum IgG Abs to the UPEC adhesin. The results suggest that the genetically linked LTXA2B acts as a useful mucosal adjuvant, and that adhesin/LTXA2A chimeric protein might be a potential antigen for oral immunization against UPEC.

• 대한두경부종양학회지
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• 제21권2호
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• pp.139-145
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• 2005

Background and Objectives: Because of squamous cell carcinoma of the head and neck undergoes a generally poor hospital course, the prognostic significance of the squamous cell carcinomas in head and neck have been evaluated to identify those features associated with aggressive biologic behavior according to the immunologic and histopathologic characteristics. Materials and Method: To assess the significance of EGFR, c-erbB-2, p21 and p53 protein in head and neck tumors and their correlation with prognostic factors, samples from 74 patients with squamous cell carcinomas of larynx, pharynx, and oral cavity were studied immunohistochemically. Results: EGFR, c-erbB-2, p21, and p53 protein were expressed 94.6%, 24.3%, 85.1%, and 55.4% in 74 cases of head and neck squamous cell carcinoma, respectively. The positive expression of EGFR was associated significantly with clinical stage and the negative expressions of p21 was associated significantly with histopathologic differentiation. There were no significant relationships between the reactivity of EGFR, c-erbB-2, p21, and p53 protein. Conclusion: The expression of EGFR, c-erbB-2, p21 and p53 protein could be related to oncogenesis, and the expression of p21 and EGFR protein can be used as a prognosticator in head and neck squamous cell carcinoma under certain limitations, but c-erbB-2 and p53 protein expression alone is not enough for evaluating prognosis of the carcinoma.

• Journal of Microbiology
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• 제43권6호
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• pp.529-536
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• 2005

Viral infection causes stress to the endoplasmic reticulum (ER). The response to endoplasmic reticulum stress, known as the unfolded protein response (UPR), is designed to eliminate misfolded proteins and allow the cell to recover. The role of hepatitis C virus (HCV) non-structural protein NS4B, a component of the HCV replicons that induce UPR, is incompletely understood. We demonstrate that HCV NS4B could induce activating transcription factor (ATF6) and inositol-requiring enzyme 1 (IRE1), to favor the HCV subreplicon and HCV viral replication. HCV NS4B activated the IRE1 pathway, as indicated by splicing of X box-binding protein (Xbp-1) mRNA. However, transcriptional activation of the XBP-1 target gene, EDEM (ER degradation-enhancing $\alpha-mannosidase-like$ protein, a protein degradation factor), was inhibited. These results imply that NS4B might induce UPR through ATF6 and IRE1-XBP1 pathways, but might also modify the outcome to benefit HCV or HCV subreplicon replication.