• Molecules and Cells
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• 제39권4호
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• pp.286-291
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• 2016

Epstein-Barr virus (EBV) is the prototypical ${\gamma}$-herpesvirus and an obligate human pathogen that infects mainly epithelial cells and B cells, which can result in malignancies. EBV infects these target cells by fusing with the viral and cellular lipid bilayer membranes using multiple viral factors and host receptor(s) thus exhibiting a unique complexity in its entry machinery. To enter epithelial cells, EBV requires minimally the conserved core fusion machinery comprised of the glycoproteins gH/gL acting as the receptor-binding complex and gB as the fusogen. EBV can enter B cells using gp42, which binds tightly to gH/gL and interacts with host HLA class II, activating fusion. Previously, we published the individual crystal structures of EBV entry factors, such as gH/gL and gp42, the EBV/host receptor complex, gp42/HLA-DR1, and the fusion protein EBV gB in a postfusion conformation, which allowed us to identify structural determinants and regions critical for receptor-binding and membrane fusion. Recently, we reported different low resolution models of the EBV B cell entry triggering complex (gHgL/gp42/HLA class II) in "open" and "closed" states based on negative-stain single particle electron microscopy, which provide further mechanistic insights. This review summarizes the current knowledge of these key players in EBV entry and how their structures impact receptor-binding and the triggering of gB-mediated fusion.

• Molecules and Cells
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• 제38권2호
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• pp.105-111
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• 2015

The beta2-adrenergic receptor (${\beta}2AR$) belongs to the G protein coupled receptor (GPCR) family, which is the largest family of cell surface receptors in humans. Extra attention has been focused on the human GPCRs because they have been studied as important protein targets for pharmaceutical drug development. In fact, approximately 40% of marketed drugs directly work on GPCRs. GPCRs respond to various extracellular stimuli, such as sensory signals, neurotransmitters, chemokines, and hormones, to induce structural changes at the cytoplasmic surface, activating downstream signaling pathways, primarily through interactions with heterotrimeric G proteins or through G-protein independent pathways, such as arrestin. Most GPCRs, except for rhodhopsin, which contains covalently linked 11 cis-retinal, bind to diffusible ligands, having various conformational states between inactive and active structures. The first human GPCR structure was determined using an inverse agonist bound ${\beta}2AR$ in 2007 and since then, more than 20 distinct GPCR structures have been solved. However, most GPCR structures were solved as inactive forms, and an agonist bound fully active structure is still hard to obtain. In a structural point of view, ${\beta}2AR$ is relatively well studied since its fully active structure as a complex with G protein as well as several inactive structures are available. The structural comparison of inactive and active states gives an important clue in understanding the activation mechanism of ${\beta}2AR$. In this review, structural features of inactive and active states of ${\beta}2AR$, the interaction of ${\beta}2AR$ with heterotrimeric G protein, and the comparison with ${\beta}1AR$ will be discussed.

• Molecules and Cells
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• 제27권1호
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• pp.89-97
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• 2009

We investigate the molecular and cellular etiologies that underlie the deletion of the six amino acid residues (${\Delta}F323-Y328$; ${\Delta}FY$) in human torsin A (HtorA). The most common and severe mutation involved with early-onset torsion dystonia is a glutamic acid deletion (${\Delta}E$ 302/303; ${\Delta}E$) in HtorA which induces protein aggregates in neurons and cells. Even though ${\Delta}FY$ HtorA forms no protein clusters, flies expressing ${\Delta}FY$ HtorA in neurons or muscles manifested a similar but delayed onset of adult locomotor disability compared with flies expressing ${\Delta}E$ in HtorA. In addition, flies expressing ${\Delta}FY$ HtorA had fewer aberrant ultrastructures at synapses compared with flies expressing ${\Delta}E$ HtorA. Taken together, the ${\Delta}FY$ mutation in HtorA may be responsible for behavioral and anatomical aberrations in Drosophila.

• Progress in Superconductivity
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• 제4권2호
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• pp.132-136
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• 2003

Extremely selective high temperature superconducting (HTS) band -pass filters were developed for the base transceiver station applications of Digital Cellular communication Service (DCS). The filters have a bandwidth of 25 MHz at a center frequency of 834 MHz. There are 12 resonators which have spiral-meander microstrip-line structures in order to reduce far-field radiations with a reasonable tunability. As a result, the size of filters is 5 mm $\times$ 17 mm $\times$ 41 mm. Device characteristics exhibited a low insertion loss of -0.4 dB with a -0.2 dB ripple and a return loss better than -10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge.

• Molecules and Cells
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• 제43권4호
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• pp.313-322
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• 2020

Eukaryotes transport biomolecules between intracellular organelles and between cells and the environment via vesicle trafficking. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE proteins) play pivotal roles in vesicle and membrane trafficking. These proteins are categorized as Qa, Qb, Qc, and R SNAREs and form a complex that induces vesicle fusion for targeting of vesicle cargos. As the core components of the SNARE complex, the SNAP25 Qbc SNAREs perform various functions related to cellular homeostasis. The Arabidopsis thaliana SNAP25 homolog AtSNAP33 interacts with Qa and R SNAREs and plays a key role in cytokinesis and in triggering innate immune responses. However, other Arabidopsis SNAP25 homologs, such as AtSNAP29 and AtSNAP30, are not well studied; this includes their localization, interactions, structures, and functions. Here, we discuss three biological functions of plant SNAP25 orthologs in the context of AtSNAP33 and highlight recent findings on SNAP25 orthologs in various plants. We propose future directions for determining the roles of the less well-characterized AtSNAP29 and AtSNAP30 proteins.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.163-166
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• 1997

Aluminium foam material is a highly porous material having complicated cellular structure defined by randomly distributed air pores in metallic matrix. this structure gives the aluminium a set of properties which cannot be achieved by any of conventional treatments. The properties of aluminium foam material significantly depend on its porosity, so that a desired profile of properties can be tailored by changing the foam density. Melting method is the one of foaming processes, which the production has long been considered difficult to realize becaues of such problems as the low foamability of molten metal, the varying size of. cellular structures, solidification shrinkage and so on. These problems, however, have gradually been solved by researchers and some manufacturers are now producing foamed aluminum by their own methods. Most of all, the parameters of solving problem in electric furnace were stirring temperature, stirring velocity, foaming temper:iture, and so on. But it has not considered about those in induction heating, foaming velocity and foaming temperature in semi-solid state yet. Therefore, this paper presents the effects on these parameter to control cell size, quantity and distribution.

• 대한세포병리학회지
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• 제13권1호
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• pp.28-32
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• 2002

Malignant myoepithelioma (myoepithelial carcinoma), is a very rare malignant epithelial accounting for less than 1% of all salivary gland tumors and has an intermediate malignant potential. We report a case of malignant myoepithelioma arising in the left parotid giand in a 54-year-old man, which was difficult to differentiate from pleomorphic adenoma and other malignant salivary gland neoplasms. Fine needle aspiration cytology of the parotid gland showed cellular smear, composed of overlapped sheets and clusters or individually scattered tumor cells without any acinic or ductal structures. The tumor cells were rather uniform, with distinct cell borders and moderate amount of cytoplasm. The eccentrically located nuclei were oval to round and pleomorphic and showed prominent nucleoli. A few clear cells were noted in the cellular aggregates Metachromatic matrix was seen between individual tumor cells in a lacelike fashion, resembling pleomorphic adenoma. According to the immunohistochemical staining, we recognized that the component cells are myoeplthelial in nature, showing reactivity for the S-100 protein, vimentin, and actin.

• Journal of Plant Biology
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• 제36권3호
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• pp.285-292
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• 1993

Cellular compatibility in the self-parasitism of Cuscuta australis R. Brown was studied at the ultrastructural level. The front cells of the haustorium penetrated the host stems independently grew within the host tissues and transformed into elongate, filamentous hyphae. Each hyphal cells contained a large nucleus and dense cytoplasm with abundant cell organelles. Multilamellar structures were contained in the cytoplasm and cell walls of the penetrating hyphal cells. When the hyphal cells did not yet invade the host cells, the middle lamella and the fused cellulosic cell walls of the two partners at the host-parasite interface were preserved well. As the invasion of the parasitic hyphal cells progressed, however, the middle lamella was not found at the interface and the host cell walls and plasma membranes were partially broken down. A hyphal cell penetrated deeply into the host cell had a more darkly stained cytoplasm with numerous of cell organelles. In the host cells attacked by the hyphal cells the limiting membranes of plastids were broken down and several vesicles were arrayed near the cell walls. No plasmodesmatal connections between the host and parasite cell walls were found; however, half-plasmodesmata were observed frequently on the side of the hyphal cell walls. These results suggested that the compatibility response in the self-parasitism of Cuscuta was expressed by cell walls, not by plasmodesmata, between the host and the parasite cells.

• 한국정보통신학회논문지
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• 제3권1호
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• pp.129-139
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• 1999

DECT(Digital Enhanced Cordless Telecommunications)는 사설교환기에 이동서비스를 제공하기 위한 통신규약으로 셀 반경이 100∼200 m 정도인 협역상의 이동서비스를 제공하는 초소형 셀룰라(pico-cellular) 방식이고, PSTN을 이용한 저가형 통신서비스를 제공함으로써 빌딩의 옥내형 이동통신을 위한 GSM의 이상적인 보완책으로 각광을 받고 있다. 본 논문에서는 링크제어, 오류제어, 시퀀스제어, 흐름제어 기능의 수행으로 상위 네트워크 계층에게 신뢰성 있는 통신 링크를 제공하고, 가입자 수용용량의 증대를 위해 증설되는 기지국과 기지국 접속장치의 위치에 무관하게 실시간 서비스를 제공할 수 있는 데이타 링크제어 계층의 구현을 위해 이의 구조와 기능을 분석하고 설계하였다.

• 대한세포병리학회지
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• 제19권1호
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• pp.47-51
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• 2008

Adenomatoid tumor is a benign neoplasm of a mesothelial origin, and it usually occurs in the reproductive organs, especially in the epididymis. The author experienced a case of adenomatoid tumor involving the tunica albuginea and testicular parenchyme without any evidence of epididymis involvement. The patient was a 36-year-old man with a painless scrotal mass that he had experienced for 2 months, and this mimicked testicular neoplasia, including metastatic carcinoma, or other benign lesions. The imprint cytology of the tumor showed a hypocellular smear with mainly arranged cells in cohesive monolayered clusters along with occasional singly dispersed cells and naked nuclei in a clean background. The cellular clusters formed vague glandular and cord-like structures. The tumor cells were large polygonal to columnar cells with a relatively monomorphic appearance. The nuclei were oval to round shape and they showed vesicular, fine chromatin and inconspicuous nucleoli. The cytoplasm was moderate to abundant, and it contained fine vacuoles in some tumor cells. Mitoses and cellular pleomorphism were not present. Awareness of the cytologic finding of this lesion is necessary to screen or differentiate a testicular or paratesticular mass before and/or during surgery because the cytology may be useful as a diagnostic tool. Pathologists should be aware of the cytologic features of common lesions in this anatomic region so as to avoid performing aggressive and unnecessary surgical procedures.