• Korean Journal of Plant Tissue Culture
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• v.27 no.4
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• pp.283-297
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• 2000

Seeds are an ideal repository for recombinant proteins in molecular farming applications. However, in order to use plant seeds efficiently for the production of such proteins, it is necessary to understand a number of fundamental biological properties of seeds. This includes a full understanding of promoters which function in a seed-specific manner, the subcellular targeting of the desired polypeptide and the final form in which a protein is stored. Once a biologically active protein has been deposited in a seed, it is also critical that the protein can be extracted and purified efficiently. In this review, these issues are examined critically to provide a number of approaches which may be adopted for production of recombinant proteins in plants. Particular attention is paid to the relationship between subcellular localization and protein extraction and purification. The robustness and flexibility of seed-based production is illustrated by examples close to or already in commercial production.

• Journal of Plant Biotechnology
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• v.4 no.3
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• pp.95-101
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• 2002

Molecular faming has the potential to provide large amounts of recombinant protein for use in diagnostics and as therapeutics. Various strategies have been developed to enhance the expression level, stability, and native folding of recombinant proteins produced in plants. Few investigations into the subcellular distribution of recombinant proteins within plant cells have been published despite the potential to increase the expression level and impact the purification process. This review article discusses the current strategies used for targeting recombinant proteins to various subcellular locations and the advantages of targeting to seed oil bodies for molecular farming applications. Specifically, the affinity capture of antibodies using recombinant oilbodies is discussed.

• Clinical and Experimental Reproductive Medicine
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• v.40 no.1
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• pp.1-6
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• 2013

Objective: Oocyte-specific homeobox 4 (Obox4) is preferentially expressed in oocytes and plays an important role in the completion of meiosis of oocytes. However, the Obox4 expression pattern has not been reported yet. In this study, we investigated the subcellular localization of Obox4 using a green fluorescent protein (GFP) fusion expression system. Methods: Three regions of Obox4 were divided and fused to the GFP expression vector. The partly deleted homeodomain (HD) regions of Obox4 were also fused to the GFP expression vector. The recombinant vectors were transfected into HEK-293T cells plated onto coated glass coverslips. The transfected cells were stained with 4',6-diamidino-2-phenylindol and photographed using a fluorescence microscope. Results: Mutants containing the HD region as well as full-length Obox4 were clearly localized to the nucleus. In contrast, the other mutants of either the N-terminal or C-terminal region without HD had impaired nuclear localization. We also found that the N-terminal and C-terminal of the Obox HD contributed to nuclear localization and the entire HD was necessary for nuclear localization of Obox4. Conclusion: Based on the results of the present study, we demonstrated that the intact HD region of Obox4 is responsible for the nuclear localization of Obox4 protein in cells.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.361-368
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• 1998

The E2 protein of HCV (hepatitis C virus) is thought to have a potential role in the development of subunit vaccines and diagnostics. To express it by the insect cell/baculovirus expression (Bacu) system, we constructed a recombinant Autographa californica nuclear polyhedrosis virus (AcIL3E2), determined the most appropriate expression conditions in terms of host cell line and culture medium, and characterized the expressed HCV E2 protein. A culture system using Trichoplusia ni BTI-TN5Bl-4 cells and SF 900IISFM medium expressed a relatively high level of HCV E2 protein. It was revealed that its glycosylation properties and subcellular localization were almost the same as the ones in the mammalian cell expression system previously reported, suggesting the recombinant HCV E2 protein derived from our Bacu system can be utilized for development of a subunit vaccine and diagnostics. Interestingly, HCV E2 protein was not degraded at all even at 43 h post-heat shock in the heat shock-induced necrotic cells, probably due to its integration into the microsomal membrane, indicating that heat shock can be employed to purify HCV E2 protein.

• Journal of Plant Biotechnology
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• v.48 no.3
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• pp.156-164
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• 2021

Spirodela polyrhiza, from the Lemnaceae family, are small aquatic plants that offer an alternative plant-based system for the expression of recombinant proteins. However, no turion transformation protocol has been established in this species. In this study, we exploited a pB7YWG2 vector harboring the eYFP gene that encodes enhanced yellow fluorescent protein (eYFP), which has been extensively used as a reporter and marker to visualize recombinant protein localization in plants. We adopted Agrobacterium tumefaciens-mediated turion transformation via vacuum infiltration to deliver the eYFP gene to turions, special vegetative forms produced by duckweeds to endure harsh conditions. Transgenic turions regenerated several duckweed fronds that exhibited yellow fluorescent emissions under a fluorescence microscope. Western blotting verified the expression of the eYFP protein. To the best of our knowledge, this is the first report of an efficient protocol for generating transgenic S. polyrhiza expressing eYFP via Agrobacterium tumefaciens-mediated turion transformation. The ability of turions to withstand harsh conditions increases the portability and versatility of transgenic duckweeds, favoring their use in the further development of therapeutic compounds in plants.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.1
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• pp.75-81
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• 2001

We have constructed a novel recombinant Bombyx mori nuclear polyhedrosis virus (BmNPV) producing the green fluorescent polyhedra. For the production of the fluorescent polyhedra, partial polyhedrin gene containing KRKK as nuclear localization site from the BmNPV polyhedrin gene and the green fluorescent protein (gfp) gene were introduced under the control of p10 promoter of BmNPV. The recombinant BmNPV was stably produced fluorescent polyhedra in the infected Bm5 cells and the morphology of the fluorescent polyhedra was similar to that of wild-type BmNPV. The fluorescent polyhedra had 32 kDa native polyhedrin and 41 kDa fusion protein. From these data, we have further developed a novel BmNPV p10-based transfer vector producing recombinant polyhedra with foreign gene Product. The novel BmNPV P10-based transfer vector is composed of partial polyhedrin gene, factor Xa, and multiple cloning sites.

• Molecules and Cells
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• v.37 no.2
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• pp.140-148
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• 2014

We identified four basic amino acid residues as nuclear localization signals (NLS) in the C-terminal domain of the prototype foamy viral (PFV) integrase (IN) protein that were essential for viral replication. We constructed seven point mutants in the C-terminal domain by changing the lysine and arginine at residues 305, 308, 313, 315, 318, 324, and 329 to threonine or proline, respectively, to identify residues conferring NLS activity. Our results showed that mutation of these residues had no effect on expression assembly, release of viral particles, or in vitro recombinant IN enzymatic activity. However, mutations at residues 305 (R ${\rightarrow}$ T), 313(R ${\rightarrow}$ T), 315(R ${\rightarrow}$ P), and 329(R ${\rightarrow}$ T) lead to the production of defective viral particles with loss of infectivity, whereas non-defective mutations at residues 308(R ${\rightarrow}$ T), 318(K ${\rightarrow}$ T), and 324(K ${\rightarrow}$ T) did not show any adverse effects on subsequent production or release of viral particles. Sub-cellular fractionation and immunostaining for viral protein PFV-IN and PFV-Gag localization revealed predominant cytoplasmic localization of PFV-IN in defective mutants, whereas cytoplasmic and nuclear localization of PFV-IN was observed in wild type and non-defective mutants. However sub-cellular localization of PFV-Gag resulted in predominant nuclear localization and less presence in the cytoplasm of the wild type and non-defective mutants. But defective mutants showed only nuclear localization of Gag. Therefore, we postulate that four basic arginine residues at 305, 313, 315 and 329 confer the karyoplilic properties of PFV-IN and are essential for successful viral integration and replication.

• BMB Reports
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• v.33 no.6
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• pp.440-447
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• 2000

In this study HepG2 cells were used to express and purify HBV pol proteins. In order to facilitate purification of HBV pol proteins, HBV pol and its deletion mutants were fused to MBP (Maltose Binding Protein). As a result we successfully expressed and partially purified both wild type and mutant recombinant HBV pol proteins by using an amylose resin and anti-MBP antibody. In the case of wild type, the anti-MBP antibody detected three bands. One was full-length and the others were generated by proteolysis of the terminal domain region. The expressed MBP/POL proteins were localized both in the cytoplasm and in the perinuclear region. The purified proteins had polymerase activity toward an exogenous homo-polymer template. The MBP/POL protein also had DNA synthesis activity in vivo, since the MBP/POL expression construct was able to complement a HBV polymerase mutant in trans.

• BMB Reports
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• v.31 no.3
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• pp.281-286
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• 1998

Hepatitis C virus (HCV) core proteins from two different isolates (HCV-1 and HCV-RH) were expressed in Spotioptera Jrugiperda (Sf9) insect cells. The RH core consisted of two major species of proteins (21 kDa and 19 kDa). On the other hand, the HCV-1 core was approximately 16 kDa in a SDS-PAGE gel. Both core proteins were phosphorylated in vivo on serine residues. Furthermore, the RH core but not HCV-1 core formed dimers, indicating that the protein conformation of the core in these two isolates is dfferent from one another. Immunofluorescence studies showed that the RH core was present in the cytoplasm, whereas the HCV-1 core was localized predominantly to the nucleus in recombinant baculovirus-infected insect cells. Since the major difference between the two isolates is the codon 9 of the core protein, a single amino acid substitution appears to play a major role in the protein conformation and these properties may reflect the different biological functions of core proteins in HCV-infected cells.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.710-716
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• 2016

Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway.