• BMB Reports
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• 제29권2호
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• pp.180-182
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• 1996

One of the essential functions of virus surface proteins is the recognition of specific receptors on target cell membranes, and cellular receptors play an important role in viral pathogenesis. But the earliest steps of hepatitis B virus (HBV) infection, such as hepatocyte receptor interaction with the virus, are poorly understood. Previous work has suggested an important role of the preS1 region of HBV envelope protein in mediating viral binding to hepatocytes. Although hepatitis B virus (HBV) infection appears to be initiated by specific binding of virions to cell membrane structures via one or potentially several viral surface proteins, data showing the identification or isolation of the HBV receptor (s) are not yet available. The receptor-like proteins on the plasma membrane surface of HepG2 cells that bind to PreS1 were separated and identified using affinity chromatography, and the amino-terminal amino acid sequences of the receptor-like proteins were determined.

• Journal of Plant Biotechnology
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• 제45권4호
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• pp.315-321
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• 2018

Molecular and functional characterization of proteins and their levels is of great interest in understanding the mechanism of diverse cellular processes. In this study, we report on the convenient Escherichia coli-based protein expression system that allows recombinant of soluble proteins expression and cytosolic domain of membrane-localised kinases, followed by the detection of autophosphorylation activity in protein kinases. This approach is applied to regulatory proteins of Arabidopsis thaliana, including 14-3-3, calmodulin, calcium-dependent protein kinase, TERMINAL FLOWER 1(TFL1), FLOWERING LOCUS T (FT), receptor-like cytoplasmic kinase and cytoplasmic domain of leucine-rich repeat-receptor like kinase proteins. Our Western blot analysis which uses phospho-specific antibodies showed that five putative LRR-RLKs and two putative RLCKs have autophosphorylation activity in vitro on threonine and/or tyrosine residue(s), suggesting their potential role in signal transduction pathways. Our findings were also discussed in the broader context of recombinant expression and biochemical analysis of soluble and membrane-localised receptor kinases in microbial systems.

• Animal cells and systems
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• 제1권2호
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• pp.341-344
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• 1997

Receptor-mediated endocytosis has been suggested for a stage-specific transport mechanism of vitellogenin into the oocytes of a sabellid poly chaete, Pseudopotamilla occelata. Membrane proteins of oocytes of three size classes, including small (30-70 $\mu\textrm{m}$ in diameter), intermediate (70-140 $\mu\textrm{m}$ in diameter) and large (180-200 $\mu\textrm{m}$ in diameter), showed a atage-specific variation. Coelomic fluid proteins (CP), ass$\mu\textrm{m}$ed to be vitellogenin, consists of several proteins, which showed quite a different pattern from that of yolk proteins. Incorporation of $^{125}I$-CP into the oocytes of the intermediate size class almost linearly increases with time, showing a contrast to the pattern of the large size class, in which the incorporation is low and approaches a plateau, suggesting the vitellogenin transports by a regulated process only in the intermediate size class. Vitellogenin receptor proteins were identified to be 60 kDa and 68 kDa only in the intermediate size class by a ligand blotting test.

• Journal of Microbiology and Biotechnology
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• 제25권2호
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• pp.247-254
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• 2015

In this presentation, I describe the expression and purification of the recombinant liver X receptor β-ligand binding domain proteins in E. coli using a commercially available double cistronic vector, pACYCDuet-1, to express the receptor heterodimer in a single cell as the soluble form. I describe here the expression and characterization of a biologically active heterodimer composed of the liver X receptor β-ligand binding domain and retinoid X receptor α-ligand binding domain. Although many of these proteins were previously seen to be produced in E. coli as insoluble aggregates or "inclusion bodies", I show here that as a form of heterodimer they can be made in soluble forms that are biologically active. This suggests that co-expression of the liver X receptor β-ligand binding domain with its binding partner improves the solubility of the complex and probably assists in their correct folding, thereby functioning as a type of molecular chaperone.

• Archives of Pharmacal Research
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• 제27권4호
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• pp.361-370
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• 2004

The discovery of insulin receptor substrate (IRS) proteins and their role to link cell surface receptors to the intracellular signaling cascades is a key step to understanding insulin and insulin-like growth factor (IGF) action. Moreover, IRS-proteins coordinate signals from the insulin and IGF receptor tyrosine kinases with those generated by proinflammatory cytokines and nutrients. The IRS2-branch of the insulin/IGF signaling cascade has an important role in both peripheral insulin response and pancreatic $\beta$-cell growth and function. Dysregulation of IRS2 signaling in mice causes the failure of compensatory hyperinsulinemia during peripheral insulin resistance. IRS protein signaling is down regulated by serine phosphorylation or protea-some-mediated degradation, which might be an important mechanism of insulin resistance during acute injury and infection, or chronic stress associated with aging or obesity. Under-standing the regulation and signaling by IRS1 and IRS2 in cell growth, metabolism and survival will reveal new strategies to prevent or cure diabetes and other metabolic diseases.

• Animal cells and systems
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• 제13권1호
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• pp.1-8
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• 2009

Toll-like receptor (TLR) family proteins, type I transmembrane proteins, play a central role in human innate immune response by recognizing common structural patterns in diverse molecules from bacteria, viruses and fungi. Recently four structures of the TLR and ligand complexes have been determined by high resolution x-ray crystallographic technique. In this review we summarize reported structures of TLRs and their proposed activation mechanisms. The structures demonstrate that binding of agonistic ligands to the extracellular domains of TLRs induces homo- or heterodimerization of the receptors. Dimerization of the TLR extracellular domains brings their two C-termini into close proximity. This suggests a plausible mechanism of TLR activation: ligand induces dimerization of the extracellular domains, which enforces juxtaposition of intracellular signaling domains for recruitment of intracellular adaptor proteins for signal initiation.

• Molecules and Cells
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• 제25권2호
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• pp.149-157
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• 2008

Dopamine is a major neurotransmitter in the mammalian central nervous system (CNS) that regulates neuroendocrine functions, locomotor activity, cognition and emotion. The dopamine system has been extensively studied because dysfunction of this system is linked to various pathological conditions including Parkinson's disease, schizophrenia, Tourette's syndrome, and drug addiction. Accordingly, intense efforts to delineate the full complement of signaling pathways mediated by individual receptor subtypes have been pursued. Dopamine D1-like receptors are of particular interest because they are the most abundant dopamine receptors in CNS. Recent work suggests that dopamine signaling could be regulated via dopamine receptor interacting proteins (DRIPs). Unraveling these DRIPs involved in the dopamine system may provide a better understanding of the mechanisms underlying CNS disorders related to dopamine system dysfunction and may help identify novel therapeutic targets.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.101-101
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• 2001

In the present study, we explored to determine if insulin has any effect on the nuclear translocation of insulin receptor and tyrosine phosphoryaltion of nuclear proteins in the UMR-106 cells. Significant amount of insulin receptors and IRS-1 proteins were detected in the nucleus. IRS-1 and PI$_3$-Kinase appeared to translocate to the nucleus in a time dependent manner. Tyrosine phosphorylation of a number of proteins including 180 KDa, 85 KDa protein in the nucleus was significantly stimulated by insulin, suggesting IRS-1 and PI$_3$-Klnase was activated in the nucleus by insulin treatment. In addition, p70 S6 Kinase, a downstream target of PI3-Kinase was transiently appeared in the nucleus by insulin and its activity was stimulated by insulin. These results suggest that the insulin signaling system containing insulin receptor, IRS-1, PI$_3$-Kinase and p70 S6 Kinase operates in the nucleus of osteoblast cells. The nuclear insulin-mediated tyrosine phosphorylation may play an essential role in the gene expression, differentiation and growth of osteoblast cells.

• BMB Reports
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• 제35권1호
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• pp.61-66
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• 2002

The TNF receptor-associated factor (TRAF) family is a group of adapter proteins that link a wide variety of cell surface receptors. Including the TNF and IL-1 receptor superfamily to diverse signaling cascades, which lead to the activation of NF-${\kappa}B$ and mitogen-activated protein kinases. In addition, TRAFs interact with a variety of proteins that regulate receptor-induced cell death or survival. Thus, TRAF-mediated signals may directly induce cell survival or interfere with the death receptor-induced apoptosis.

• Animal cells and systems
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• 제2권2호
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• pp.153-164
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• 1998

Cytokines regulate proliferation, differentiation and functions of haemotopoietic cells. Each cytokine possesses a variety of activities on various target cells (pleiotropy) and various cytokines have similar and overlapping activities on the same target cells (redundancy). The nature of these cytokine activities predicts unique feature of cytokine receptors, namely, cytokine has multiple receptors, different cytokines share a common receptor, and different cytokine receptors are linked to common signaling pathways. cDNA cloning of genes for cytokine receptors revealed distinct sets of receptor family with different structural features. The cytokine receptor superfamily consists of a largest family, and contains more than twenty cytokine receptor subunits. This receptor has common structural features in both extracellular and intracellular regions without tyrosine kinase domain. Another striking feature of the receptor is to share common subunit of multiple cytokines, which partly explains the redundancy of activities of some cytokines. Recent studies revealed detailed signaling events of the cytokine receptor, the primary activation of JAK and subsequent phosphorylation of tyrosine residues of receptor, and various cellular proteins. Many SH2 containing adapter proteins play an important role in cytokine signals, and this system has similarities with tyrosine kinase receptor signal transduction. STAT may mainly account for cytokine specific functions as suggested by knockout mice studies. It is of importance to note that cytokine activates multiple signaling pathways and the balance and combination of related signaling events may determine the specificity of functions of cytokines.