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Kang, Hyun Ju,Aziz, Md. Abdul,Jeon, Boyoun,Jo, Kyungmin,Yang, Haesik WILEY-VCH Verlag 2009 Electroanalysis Vol.21 No.24
<P>This article describes an electrochemical strategy to achieve low background-current levels in horse-radish peroxidase (HRP)-based electrochemical immunosensors. The strategy consists of (i) the use of an HRP substrate/product redox couple whose formal potential is high and (ii) the use of an electrode that shows moderate electrocatalytic activity for the redox couple. The strategy is proved by a model biosensor using a catechol/o-benzoquinone redox couple and an indium tin oxide (ITO) electrode. The combined effect of high formal potential and moderate electrocatalytic activity allows o-benzoquinone electroreduction with minimal catechol electrooxidation and H<SUB>2</SUB>O<SUB>2</SUB> electroreduction. The detection limit for mouse-IgG is 100 pg/mL.</P>
A role for protein disulfide isomerase in the early folding and assembly of MHC class I molecules.
Kang, Kwonyoon,Park, Boyoun,Oh, Changhoon,Cho, Kwangmin,Ahn, Kwangseog Mary Ann Liebert, Inc 2009 ANTIOXIDANTS AND REDOX SIGNALING Vol.11 No.10
<P>Proper folding and assembly of major histocompatibility complex (MHC) class I complexes are essential for optimal peptide loading and subsequent antigen presentation. MHC class I folding involves the coordinated formation of multiple disulfide bonds within MHC class I molecules. However, the regulation of disulfide bond formation during the early process of MHC class I folding is uncharacterized. Here, we show that protein disulfide isomerase (PDI) catalyzes the disulfide bond formation of MHC class I molecules and thereby facilitates the assembly of MHC class I heavy chain with beta(2)-microglobulin (beta(2)m). Depletion of PDI but not ERp57 by RNAi interfered with the disulfide bond formation in the MHC class I molecules. In the absence of PDI, the association of free class I heavy chain with calnexin increased, whereas the assembly of MHC class I heavy chain-beta(2)m heterodimers was delayed. These observations suggest that PDI-catalyzed disulfide bond formation of MHC class I molecules is an event downstream of the interaction of class I molecules with calnexin and upstream of their interaction with beta(2)m. Thus, our data establish a critical function for PDI in the early assembly of MHC class I molecules.</P>
Lee, Sungwook,Park, Boyoun,Kang, Kwonyoon,Ahn, Kwangseog American Society for Cell Biology 2009 Molecular biology of the cell Vol.20 No.14
<P>In contrast to the fairly well-characterized mechanism of assembly of MHC class I-peptide complexes, the disassembly mechanism by which peptide-loaded MHC class I molecules are released from the peptide-loading complex and exit the endoplasmic reticulum (ER) is poorly understood. Optimal peptide binding by MHC class I molecules is assumed to be sufficient for triggering exit of peptide-filled MHC class I molecules from the ER. We now show that protein disulfide isomerase (PDI) controls MHC class I disassembly by regulating dissociation of the tapasin-ERp57 disulfide conjugate. PDI acts as a peptide-dependent molecular switch; in the peptide-bound state, it binds to tapasin and ERp57 and induces dissociation of the tapasin-ERp57 conjugate. In the peptide-free state, PDI is incompetent to bind to tapasin or ERp57 and fails to dissociate the tapasin-ERp57 conjugates, resulting in ER retention of MHC class I molecules. Thus, our results indicate that even after optimal peptide loading, MHC class I disassembly does not occur by default but, rather, is a regulated process involving PDI-mediated interactions within the peptide-loading complex.</P>
Shin, Jinwook,Park, Boyoun,Lee, Sungwook,Kim, Youngkyun,Biegalke, Bonita J.,Kang, Seongman,Ahn, Kwangseog American Society for Microbiology 2006 Journal of virology Vol.80 No.11
<B>ABSTRACT</B><P>Human cytomegalovirus encodes four unique short (US) region proteins, each of which is independently sufficient for causing the down-regulation of major histocompatibility complex (MHC) class I molecules on the cell surface. This down-regulation enables infected cells to evade recognition by cytotoxic T lymphocytes (CTLs) but makes them vulnerable to lysis by natural killer (NK) cells, which lyse those cells that lack MHC class I molecules. The 22-kDa US3 glycoprotein is able to down-regulate the surface expression of MHC class I molecules by dual mechanisms: direct endoplasmic reticulum retention by physical association and/or tapasin inhibition. The alternative splicing of the <I>US3</I> gene generates two additional products, including 17-kDa and 3.5-kDa truncated isoforms; however, the functional significance of these isoforms during viral infection is unknown. Here, we describe a novel mode of self-regulation of US3 function that uses the endogenously produced truncated isoform. The truncated isoform itself neither binds to MHC class I molecules nor prevents the full-length US3 from interacting with MHC class I molecules. Instead, the truncated isoform associates with tapasin and competes with full-length US3 for binding to tapasin; thus, it suppresses the action of US3 that causes the disruption of the function of tapasin. Our results indicate that the truncated isoform of the <I>US3</I> locus acts as a dominant negative regulator of full-length US3 activity. These data reflect the manner in which the virus has developed temporal survival strategies during viral infection against immune surveillance involving both CTLs and NK cells.</P>
Min Chul-Hee,Kang Boyoun,Cho Beong Ki,Cho En-Jin,Park Byeong-Gyu,김형도 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.8
Temperature-dependent angle-resolved photoemission spectroscopy (ARPES) was carried out on single-crystalline EuB6 samples. By measuring ARPES spectra in an extended Brillouin zone, we clearly observed a B 2p hole pocket centered at the X point, thus proving the semimetallic nature of EuB6 . Below the Curie temperature T C , ARPES spectra show two B 2p bands of which separation is due to an exchange interaction between local Eu 4f and itinerant B 2p electrons. The exchange splitting becomes smaller as the temperature increases and disappears well above T C . Additionally, a diffuse structure near the Fermi level survives at temperatures just above T C . Such behavior is well described by using Monte Carlo simulations of a Kondo-lattice model, thus supporting the formation of magnetic polarons in EuB6 , which accounts for the resistivity upturn slightly above T C as the temperature is lowered.
Survey of bovine norovirus infections from diarrheic calves in South Korea, 2015-2017
Lee, Eun-Yong,Kang, Hyung-Woo,Kim, Ha-Young,Kim, Seong-Hee,Moon, Boyoun,So, Byung Jae,Lee, Kyoung-Ki,Kim, Yeon-Hee The Korean Society of Veterinary Science 2019 大韓獸醫學會誌 Vol.59 No.1
This study examined complex infections with various enteropathogens and the genetic diversity of bovine norovirus (BNoV) in 932 fecal samples from diarrheic calves in South Korea. Overall, seventeen (1.8%) of the samples tested positive for BNoV following RT-PCR examination. All BNoV-positive samples were co-infected with other intestinal pathogens, including bovine Rotavirus, Giardia, Cryptosporidium, and Escherichia coli. The genetic diversity of the BNoVs shared high nucleotide identity (98.1-99.5%) and amino acid homology (93.5-98.1%) with genotype 2 BNoV (GIII.2) strains. In conclusion, BNoV infections with GIII genotypes were detected in complex infections of diarrheic calves in South Korea.
Nguyen, Thi Huyen,Nguyen, Thi Minh Hien,Kang, Boyoun,Cho, Beongki,Park, Yeonju,Jung, Young Mee,Yang, In-Sang Elsevier 2018 Journal of molecular structure Vol.1165 No.-
<P><B>Abstract</B></P> <P>2D correlation analysis (2DCOS) and principal component analysis (PCA) have been performed on temperature-dependent Raman spectra from 12 K to 300 K of SmB<SUB>6</SUB> single crystals grown from Boron with a purity of 99.9% (3N) or 99.9999% (6N). Significant differences in the Raman spectra of SmB<SUB>6</SUB>(3N) and SmB<SUB>6</SUB>(6N) are observed. The Raman active T<SUB>2g</SUB>, E<SUB>g</SUB>, and A<SUB>1g</SUB> modes of SmB<SUB>6</SUB>(3N) are broader and shift to higher wavenumbers compared with those of SmB<SUB>6</SUB>(6N). The results of 2DCOS and PCA on temperature-dependent Raman spectra of SmB<SUB>6</SUB>(3N) and SmB<SUB>6</SUB>(6N) give us further information. We find that all the T<SUB>2g</SUB>, E<SUB>g</SUB>, and A<SUB>1g</SUB> modes of SmB<SUB>6</SUB>(6N) are single bands, while those of SmB<SUB>6</SUB>(3N) show all doublet features. The appearance of multiple bands in Raman vibrational modes of SmB<SUB>6</SUB>(3N) sample implies that the structure of boron octahedra of the SmB<SUB>6</SUB>(3N) has lower symmetry than that of SmB<SUB>6</SUB>(6N). Our findings in 2DCOS and PCA of the Raman spectra strongly support the differences in the behavior of SmB<SUB>6</SUB>(3N) and SmB<SUB>6</SUB>(6N).</P> <P><B>Highlights</B></P> <P> <UL> <LI> The symmetry of the boron octahedra in SmB<SUB>6</SUB> is found to be lowered by small amount of impurities in boron ingredient. </LI> <LI> Raman spectra of SmB<SUB>6</SUB> single crystals strongly depend on the Boron purity. </LI> <LI> 2DCOS and PCA show the multiple bands in the Raman modes of SmB6 made of 99.9% (3N) boron. </LI> </UL> </P>
Hyeong-Do Kim,Chul-Hee Min,Boyoun Kang,Beong Ki Cho,En-Jin Cho,Byeong-Gyu Park 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
Temperature-dependent angle-resolved photoemission spectroscopy (ARPES) was carried out on single-crystalline EuB6 samples. By measuring ARPES spectra in an extended Brillouin zone, we clearly observed a B 2p hole pocket centered at the X point as shown in Fig. 1, thus proving the semimetallic nature of EuB6. Below the Curie temperature TC, ARPES spectra show two B 2p bands of which separation is due to an exchange interaction between local Eu 4f and itinerant B 2p electrons. The exchange splitting becomes smaller as the temperature increases and disappears well above TC. Additionally, a diffuse structure near the Fermi level survives at temperatures just above TC. Such behavior is well described by using Monte Carlo simulations of a Kondo lattice model, thus supporting the formation of magnetic polarons in EuB6, which accounts for the resistivity upturn slightly above TC as the temperature is lowered. 〈그림 본문참조〉
CNBP acts as a key transcriptional regulator of sustained expression of interleukin-6
Lee, Eunhye,Lee, Taeyun A.,Kim, Ji Hyun,Park, Areum,Ra, Eun A.,Kang, Sujin,Choi, Hyun jin,Choi, Junhee L.,Huh, Hyunbin D.,Lee, Ji Eun,Lee, Sungwook,Park, Boyoun Oxford University Press 2017 Nucleic acids research Vol.45 No.6
<P><B>Abstract</B></P><P>The transcription of inflammatory genes is an essential step in host defense activation. Here, we show that cellular nucleic acid-binding protein (CNBP) acts as a transcription regulator that is required for activating the innate immune response. We identified specific CNBP-binding motifs present in the promoter region of sustained inflammatory cytokines, thus, directly inducing the expression of target genes. In particular, lipopolysaccharide (LPS) induced <I>cnbp</I> expression through an NF-κB-dependent manner and a positive autoregulatory mechanism, which enables prolonged <I>il-6</I> gene expression. This event depends strictly on LPS-induced CNBP nuclear translocation through phosphorylation-mediated dimerization. Consequently, <I>cnbp</I>-depleted zebrafish are highly susceptible to <I>Shigella flexneri</I> infection <I>in vivo</I>. Collectively, these observations identify CNBP as a key transcriptional regulator required for activating and maintaining the immune response.</P>