• Membrane Journal
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• v.10 no.2
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• pp.83-91
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• 2000

In order to improve functional properties, enzymatic hydrolysis of FPC (fish protein concentration) was achieved in ultrafiltration membrane reactor (MWCO 5,000). First, insoluble FPC was hydrolyzed by pepsin in batch reactor to decrease the fouling in ultrafiltration membrane reactor, and second hydrolysis was achieved by pronase E in ultrafiltration membrane reactor The optimum operating conditions in batch reactor using pepsin were at temperature 45$^{\circ}C$, pH 2.0 and the ratio of substrate to pepsin, 150 (w/w) After operating for 5hrs under optimum conditions, 89％ of total amount of initial FPC was hydrolyzed. The rate constants, $K_{m}$ and V$_{max}$, were 1.25％ and 0.89 mg/$m\ell$/min, respectively, and substrate inhibition was occured above 1.5％. The ultrafiltration membrane reactor was operated with recycling rate of 474 $m\ell$/min and transmembrane pressure of 15 psi. The permeate flux was increased by temperature, transmembrane pressure, but the permeate flux was fixed by pH. The optimum ratio of substrate to pronase E was 200(w/w) and the productivity of ultrafiltration membarane reactor was 702 mg/mg -enzyme, that of batch reactor was 51mg/mg-enzyme. Molecular weight distributions tot first and second hydrolysates were from 2,500 Da to 20,000 Da and from 700 Da to 10,000 Da, respectivelyly.

• Journal of Life Science
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• v.25 no.4
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• pp.473-480
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• 2015

The endoplasmic reticulum (ER) in the eukaryotic cells is the first compartment in the secretory pathway. Almost secretory proteins and membrane proteins are secreted through the ER, in which post-translational modifications occur via diverse signals from the ER lumen to the cytoplasm and nucleus. Only then are correctly-folded proteins secreted to the outside cells. Unfolded proteins that accumulate in the ER cause a kind of intracellular stress, ER stress, and activate an unfolded protein response (UPR) system. The 3 major transducers of the UPR are inositol requiring 1 (IRE1), PKR-like ER kinase (PERK) and activating transcription factor 6 (ATF6), all of which are ER transmembrane proteins. Recently, novel types of a new ATF6 family have been identified. Those commonly have an ER-transmembrane domain, a transcription-activation domain and a basic leucine zipper (bZIP) domain―Luman, OASIS, BBF2H7, CREBH and CREB4. Each factor functions by regulating the UPR in specific organs and tissues. Although the detailed molecular mechanisms of OASIS family members are unknown, in this study we comprehensively introduce these molecular signals.

• BMB Reports
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• v.33 no.6
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• pp.483-492
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• 2000

The Herpes simplex virus type 1 (HSV-1) strain F glycoprotein H (gH) gene in the pHLB-4 plasmid was recombinated into a baculovirus expression vector (lacZ-HcNPV) to construct a recombinant virus GH-HcNPV expressing gH. The sequences of gH and its expression were analyzed. The gH gene was located in the 6.41 kb BglII fragment. The open reading frame (ORF) of the gH gene was 2,517 bp and codes 838 amino acid residues. Insect cells infected with this recombinant virus synthesized a high level of the matured and gX-gH fusion protein with approximately 112 kDa. The fusion gH protein was localized on the membrane of the insect cells as seen by using immunofluorescence assay and accumulated in the cultured media by the SDS-PAGE and immunoprecipitation assays. The amino acid sequence presents additional characteristics compatible with the structure of a viral glycoprotein: signal peptide, putative glycosylation sites and a long C-terminal transmembrane sequence. Antibodies raised in mice to this recombinant protein recognized viral gH and neutralized the infectivity of HSV-1 in vitro. These results demonstrate that it is possible to produce a mature protein by gene transfer in eukaryotic cells, and indicate the utility of the HcNPV-insect cell system for producing and characterizing eukaryotic proteins. Furthermore, the neutralizing antibodies would appear to protect mice against HSV; accordingly, this particular recombinant protein may be useful in the development of a subunit vaccine.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.847-858
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• 2007

The endoplasmic reticulum (ER) is an important intracellular organelle for folding and maturation of newly synthesized transmembrane and secretory proteins. The ER provides stringent quality control systems to ensure that only correctly folded proteins exit the ER and unfolded or misfolded proteins are retained and ultimately degraded. The ER has evolved stress response both signaling pathways the unfolded protein response (UPR) to cope with the accmulation of unfolded or misfolded proteins and ER overload response (EOR). Accumulating evidence suggests that, in addition to responsibility for protein processing, ER is also an important signaling compartment and a sensor of cellular stress. In this respect, production of bio-functional recombinant-proteins requires efficient functioning of the ER secretory pathway in host cells. This review briefly summarizes our understanding of the ER signaling developed in the recent years to help of the secretion capacities of recombinant cells.

• Molecules and Cells
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• v.38 no.2
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• pp.180-186
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• 2015

Escherichia coli AcrAB-TolC is a multidrug efflux pump that expels a wide range of toxic substrates. The dynamic nature of the binding or low affinity between the components has impeded elucidation of how the three components assemble in the functional state. Here, we created fusion proteins composed of AcrB, a transmembrane linker, and two copies of AcrA. The fusion protein exhibited acridine pumping activity, suggesting that the protein reflects the functional structure in vivo. To discern the assembling mode with TolC, the AcrBA fusion protein was incubated with TolC or a chimeric protein containing the TolC aperture tip region. Three-dimensional structures of the complex proteins were determined through transmission electron microscopy. The overall structure exemplifies the adaptor bridging model, wherein the funnel-like AcrA hexamer forms an intermeshing cogwheel interaction with the ${\alpha}$-barrel tip region of TolC, and a direct interaction between AcrB and TolC is not allowed. These observations provide a structural blueprint for understanding multidrug resistance in pathogenic Gram-negative bacteria.

• BMB Reports
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• v.48 no.12
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• pp.696-701
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• 2015

Toll-like receptor 3 (TLR3) recognizes viral double-stranded RNA. It stimulates pro-inflammatory cytokine and interferon production. Here we reported the expression of a novel isoform of TLR3 in human astrocyte cell lines whose message is generated by alternative splicing. The isoform represents the N-terminus of the protein. It lacks many of the leucine-rich repeat domains, the transmembrane domain, and the intracellular Toll/interleukin-1 receptor domain of TLR3. Type I interferons (interferon-α and interferon-β) induced the expression of this isoform. Exogenous overexpression of this isoform inhibited interferon regulatory factor 3, signal transducers and activators of transcription 1, and Inhibitor of kappa B α signaling following stimulation. This isoform of TLR3 also inhibited the production of chemokine interferon-γ-inducible protein 10. Our study clearly demonstrated that the expression of this isoform of TLR3 was a negative regulator of signaling pathways and that it was inducible by type I interferons. We also found that this isoform could modulate inflammation in the brain.

• BMB Reports
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• v.42 no.10
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• pp.691-696
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• 2009

The E2F gene family appears to regulate the proliferation and differentiation of events that are required for adipogenesis. Pref-1 is a transmembrane protein that inhibits adipocyte differentiation in 3T3-L1 cells. In this study, we found that the expression of pref-1 is regulated by the transcription factor E2F1. The expression of pref-1 and E2F1 was strongly induced in preadipocytes and at the late differentiation stage. Using luciferase reporter assay, ChIP assay and EMSA, we found that the -211/-194 region of the pref-1 promoter is essential for the binding of E2F1 as well as E2F1-dependent transcriptional activation. Knockdown of E2F1 reduced both pref-1 promoter activity and the level of pref-1 mRNA. Taken together, our data suggest that transcriptional activation of pref-1 is stimulated by E2F1 protein in adipocytes.

• Biomolecules & Therapeutics
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• v.25 no.1
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• pp.69-79
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• 2017

Viruses continue to evolve a new strategy to take advantage of every aspect of host cells in order to maximize their survival. Due to their central roles in transducing a variety of transmembrane signals, GPCRs seem to be a prime target for viruses to pirate for their own use. Incorporation of GPCR functionality into the genome of herpesviruses has been demonstrated to be essential for pathogenesis of many herpesviruses-induced diseases. Here, we introduce US28 of human cytomegalovirus (HCMV) as the best-studied example of virally-encoded GPCRs to manipulate host GPCR signaling. In this review, we wish to summarize a number of US28-related topics including its regulation of host signaling pathways, its constitutive internalization, its structural and functional analysis, its roles in HCMV biology and pathogenesis, its proliferative activities and role in oncogenesis, and pharmacological modulation of its biological activities. This review will aid in our understanding of how pathogenic viruses usurp the host GPCR signaling for successful viral infection. This kind of knowledge will enable us to build a better strategy to control viral infection by normalizing the virally-dysregulated host GPCR signaling.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.3
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• pp.139-145
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• 2009

The purpose of this study was to evaluate the effects of the water extract of Samultang (SMT), a Chinese herb, on apoptotic cell death by $H_2O_2$-induced oxidative stress in SK-N-M C cells. A nuclear fragmentation was observed via fluorescence imaging 12 h after exposure to 30 ${\mu}M$ $H_2O_2$ and DNA laddering was detected via agarose electrophoresis gel. In addition, increases in sub-G1 phase and cleavage of the PARP protein were observed. However, treatment with SMT for 2 h prior to $H_2O_2$ exposure significantly reduced apoptotic cell death induced by incubation with 30 ${\mu}M$ $H_2O_2$ in SK-N-MC cells. Pre-incubation with water extract of SMT for 2 h prevented the $H_2O_2$-induced decrease in mitochondrial transmembrane potential. SMT also attenuated the increase in caspase-3 activity and the breakdown of PARP protein caused by $H_2O_2$-induced oxidative stress. These results suggest that the water extract of SMT provides inhibition of apoptotic cell death against oxidative injury in SK-N-MC cells.

• Current Research on Agriculture and Life Sciences
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• v.30 no.1
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• pp.1-11
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• 2012

We identified cdf based on screening of the Arabidopsis cDNA library for functional suppressors of the AtBI-1 (a gene described to suppress the cell death induced by Bax gene expression in yeast). The cdf was located on Chr. V and was composed of 5 exons and 4 introns. It encodes a protein of 258 amino acid residues with a molecular weight of 28.8 kDa. The protein has 3 transmembrane domains in the C-terminal region. The cdf has one homologue, named cdf2, which was found in Arabidopsis. Like cdf, cdf2 also induced growth defect in yeast. The effect of the cell growth defect factor was somewhat lower than Bax. cdf could arrest the growth of yeast. Its localization to the nucleus was essential for the suppression of yeast cell proliferation. Morphological abnormality of intracellular network, which is a hallmark of AtBI-1, was attenuated by expression of cdf.