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Cloning and Expression of Human Immunodeficiency Virus - 1 Epitopes in E . Coli
Nham, Sang Uk,Lee, Young Ik,Yoo, Hyang Sook,Hyun, Sang Won,Jang, Won Hee,Park, Huei Dong 한국유전학회 1990 Genes & Genomics Vol.12 No.4
Human immunodeficiency virus type 1 (HIV-1) causes a deadly infectious disease, Acquired Immunodeficiency Syndrome (AIDS). As a first step to develop a reliable and fast diagnostic procedures for HIV-1 infection, we cloned various immunodominant epitopes of HIV-1 in bacterial expression vectors containing tac or trp promoters. While the protein level of direct expression of gp160 was low, trp E fused gp120, gp41 and p17-Op24 were produced at high levels (15-30% of total bacterial proteins) in E. coli. Since gp120 and gp41 contain relatively conserved regions which can react with antibodies in the plasma from most of HIV-1 infected individuals, these expression clones were used for large preparations of HIV-1 antigens. Purified antigens will be used for making rapid, and sensitive AIDS-diagnostic kits using whole blood systems.
Nham, Sang Uk,Choi, Eui Yul,Yie, Se Won,Lee, Kyung Mee,Chung, So Young,Chun, Gie Taek,Kim, Pyeung Hyun 생화학분자생물학회 1981 BMB Reports Vol.29 No.5
Previous studies have shown that transforming growth factor beta (TGF-β) is a potent regulator of cell growth and differentiation. To study the effects of TGF-β on cell morphology and cytoskeleton reorganization, we conducted a survey using Mv1Lu mink lung epithelial cells with antibodies to cytoskeletal proteins and an extracellular matrix protein. While the untreated cells showed a cuboidal shape of typical epithelia, the Mv1Lu cells displayed a drastic shape change in the presence of TGF-β. This alteration was most prominent when near-confluent cells were treated with TGF-β. Since the morphology alteration is known to be accompanied by the reorganization of cytoskeletal proteins in other cell types, we investigated the intracellular distribution of the three major cytoskeletal structures: microfilaments, microtubules, and intermediate filaments. In the microfilament system, TGF-β induced new stress fiber formation, which was caused primarily by the polymerization of cytoplasmic G-actin. However, TGF-β appeared not to induce any significant changes in microtubular structures and vimentin filaments as determined by indirect fluorescence microscopy. Finally we confirmed the rapid accumulation of fibronectin by immunoblot analysis and chased the protein locations by immunofluorescence microscopy.
Binding of Fibrinogen to Specific receptors on Rat Peritoneal Macrophages
Nham, Sang Uk,Fuller, Gerald M 생화학분자생물학회 1975 BMB Reports Vol.27 No.6
Binding of fibrinogen to specific receptors on rat peritineal macrophages was characterized. Fibrinogen receptors on rat peritoneal macrophages bind the fragment D domains of fibrinogen molecules, suggesting possible involvement of Mac-1 in fibrinogen binding. Receptor-fragment D interaction was reversible and reached equilibrium after 60 min incubation at 4℃. Scatchard analysis of fragment D binding indicated a single class of receptors, a binding dissociation constant of 3.8 μM, approximately 9.0 × 10^5 receptors per cell.
Characterization of αX I-Domain Binding to Receptors for Advanced Glycation End Products (RAGE)
Buyannemekh, Dolgorsuren,Nham, Sang-Uk Korean Society for Molecular and Cellular Biology 2017 Molecules and cells Vol.40 No.5
The ${\beta}2$ integrins are cell surface transmembrane proteins regulating leukocyte functions, such as adhesion and migration. Two members of ${\beta}2$ integrin, ${\alpha}M{\beta}2$ and ${\alpha}X{\beta}2$, share the leukocyte distribution profile and integrin ${\alpha}X{\beta}2$ is involved in antigen presentation in dendritic cells and transendothelial migration of monocytes and macrophages to atherosclerotic lesions. ${\underline{R}}eceptor$ for ${\underline{a}}dvanced$ ${\underline{g}}lycation$ ${\underline{e}}nd$ ${\underline{p}}roducts$ (RAGE), a member of cell adhesion molecules, plays an important role in chronic inflammation and atherosclerosis. Although RAGE and ${\alpha}X{\beta}2$ play an important role in inflammatory response and the pathogenesis of atherosclerosis, the nature of their interaction and structure involved in the binding remain poorly defined. In this study, using I-domain as a ligand binding motif of ${\alpha}X{\beta}2$, we characterize the binding nature and the interacting moieties of ${\alpha}X$ I-domain and RAGE. Their binding requires divalent cations ($Mg^{2+}$ and $Mn^{2+}$) and shows an affinity on the sub-micro molar level: the dissociation constant of ${\alpha}X$ I-domains binding to RAGE being $0.49{\mu}M$. Furthermore, the ${\alpha}X$ I-domains recognize the V-domain, but not the C1 and C2-domains of RAGE. The acidic amino acid substitutions on the ligand binding site of ${\alpha}X$ I-domain significantly reduce the I-domain binding activity to soluble RAGE and the alanine substitutions of basic amino acids on the flat surface of the V-domain prevent the V-domain binding to ${\alpha}X$ I-domain. In conclusion, the main mechanism of ${\alpha}X$ I-domain binding to RAGE is a charge interaction, in which the acidic moieties of ${\alpha}X$ I-domains, including E244, and D249, recognize the basic residues on the RAGE V-domain encompassing K39, K43, K44, R104, and K107.
Moieties of Complement iC3b Recognized by the I-domain of Integrin αXβ2
Choi, Jeongsuk,Buyannemekh, Dolgorsuren,Nham, Sang-Uk Korean Society for Molecular and Cellular Biology 2020 Molecules and cells Vol.43 No.12
Complement fragment iC3b serves as a major opsonin for facilitating phagocytosis via its interaction with complement receptors CR3 and CR4, also known by their leukocyte integrin family names, αMβ2 and αXβ2, respectively. Although there is general agreement that iC3b binds to the αM and αX I-domains of the respective β2-integrins, much less is known regarding the regions of iC3b contributing to the αX I-domain binding. In this study, using recombinant αX I-domain, as well as recombinant fragments of iC3b as candidate binding partners, we have identified two distinct binding moieties of iC3b for the αX I-domain. They are the C3 convertase-generated N-terminal segment of the C3b α'-chain (α'NT) and the factor I cleavage-generated N-terminal segment in the CUBf region of α-chain. Additionally, we have found that the CUBf segment is a novel binding moiety of iC3b for the αM I-domain. The CUBf segment shows about a 2-fold higher binding activity than the α'NT for αX I-domain. We also have shown the involvement of crucial acidic residues on the iC3b side of the interface and basic residues on the I-domain side.