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Search Results: 1 - 10 of 15262 matches for " Hyun Ho Park "
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Structural Features of Caspase-Activating Complexes
Hyun Ho Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044807
Abstract: Apoptosis, also called programmed cell death, is an orderly cellular suicide program that is critical for the development, immune regulation and homeostasis of a multi-cellular organism. Failure to control this process can lead to serious human diseases, including many types of cancer, neurodegenerative diseases, and autoimmununity. The process of apoptosis is mediated by the sequential activation of caspases, which are cysteine proteases. Initiator caspases, such as caspase-2, -8, -9, and -10, are activated by formation of caspase-activating complexes, which function as a platform to recruit caspases, providing proximity for self-activation. Well-known initiator caspase-activating complexes include (1) DISC (Death Inducing Signaling Complex), which activates caspases-8 and 10; (2) Apoptosome, which activates caspase-9; and (3) PIDDosome, which activates caspase-2. Because of the fundamental biological importance of capases, many structural and biochemical studies to understand the molecular basis of assembly mechanism of caspase-activating complexes have been performed. In this review, we summarize previous studies that have examined the structural and biochemical features of caspase-activating complexes. By analyzing the structural basis for the assembly mechanism of the caspase-activating complex, we hope to provide a comprehensive understanding of caspase activation by these important oligomeric complexes.
Structural Basis of Membrane Trafficking by Rab Family Small G Protein
Hyun Ho Park
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14058912
Abstract: The Ras-superfamily of small G proteins is a family of GTP hydrolases that is regulated by GTP/GDP binding states. One member of the Ras-superfamily, Rab, is involved in the regulation of vesicle trafficking, which is critical to endocytosis, biosynthesis, secretion, cell differentiation and cell growth. The active form of the Rab proteins, which contains GTP, can recruit specific binding partners, such as sorting adaptors, tethering factors, kinases, phosphatases and motor proteins, thereby influencing vesicle formation, transport, and tethering. Many Rab proteins share the same interacting partners and perform unique roles in specific locations. Because functional loss of the Rab pathways has been implicated in a variety of diseases, the Rab GTPase family has been extensively investigated. In this review, we summarize Rab GTPase- mediated membrane trafficking while focusing on the structures of Rab protein and Rab-effector complexes. This review provides detailed information that helps explain how the Rab GTPase family is involved in membrane trafficking.
Purification, Crystallization and Preliminary X-ray Crystallographic Studies of RAIDD Death-Domain (DD)
Tae-ho Jang,Hyun Ho Park
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10062501
Abstract: Caspase-2 activation by formation of PIDDosome is critical for genotoxic stress induced apoptosis. PIDDosome is composed of three proteins, RAIDD, PIDD, and Caspase-2. RAIDD is an adaptor protein containing an N-terminal Caspase-Recruiting-Domain (CARD) and a C-terminal Death-Domain (DD). Its interactions with Caspase-2 and PIDD through CARD and DD respectively and formation of PIDDosome are important for the activation of Caspase-2. RAIDD DD cloned into pET26b vector was expressed in E. coli cells and purified by nickel affinity chromatography and gel filtration. Although it has been known that the most DDs are not soluble in physiological condition, RAIDD DD was soluble and interacts tightly with PIDD DD in physiological condition. The purified RAIDD DD alone has been crystallized. Crystals are trigonal and belong to space group P3121 (or its enantiomorph P3221) with unit-cell parameters a = 56.3, b = 56.3, c = 64.9 ? and γ = 120°. The crystals were obtained at room temperature and diffracted to 2.0 ? resolution.
Novel Disulfide Bond-Mediated Dimerization of the CARD Domain Was Revealed by the Crystal Structure of CARMA1 CARD
Tae-ho Jang, Jin Hee Park, Hyun Ho Park
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079778
Abstract: CARMA1, BCL10 and MALT1 form a large molecular complex known as the CARMA1 signalosome during lymphocyte activation. Lymphocyte activation via the CARMA1 signalosome is critical to immune response and linked to many immune diseases. Despite the important role of the CARMA1 signalosome during lymphocyte activation and proliferation, limited structural information is available. Here, we report the dimeric structure of CARMA1 CARD at a resolution of 3.2 ?. Interestingly, although CARMA1 CARD has a canonical six helical-bundles structural fold similar to other CARDs, CARMA1 CARD shows the first homo-dimeric structure of CARD formed by a disulfide bond and reveals a possible biologically important homo-dimerization mechanism.
Geodesic Motions in 2+1 Dimensional Charged Black Holes
Dong Hyun Park,Seung-ho Yang
Physics , 1999, DOI: 10.1023/A:1026733026282
Abstract: We study the geodesic motions of a test particle around 2+1 dimensional charged black holes. We obtain a class of exact geodesic motions for the massless test particle when the ratio of its energy and angular momentum is given by square root of cosmological constant. The other geodesic motions for both massless and massive test particles are analyzed by use of numerical method.
Polymyxin B Alleviates Angiotensin II-Induced Stress Fiber Formation and Cellular Hypertrophy  [PDF]
Kwang-Seok Oh, Jeong Hyun Lee, Byung Koo Oh, Jihye Mun, Byung Kil Park, Byung Ho Lee
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.59101

Polymyxin B is widely used antibiotic in the clinic for resistant Gram-negative infections. In addition, polymyxin B-immobilized hemoperfusion cartridge has been used for endotoxin removal therapy in patients with septic shock. The aim of this study was to investigate the anti-fibrotic and anti-cellular hypertrophic effects of polymyxin B, and further to explore its possible mechanism. Polymyxin B (3, 10 μM) significantly inhibited stress fiber formation induced by angiotensin II (Ang II) in rat heart-derived H9c2 cells. Furthermore, polymyxin B (1 - 10 μM) showed a potent inhibitory effect on Ang II-induced cellular hypertrophy in H9c2 cells. Under the mechanism study, the inhibitory activities of polymyxin B against kinases involved in cellular hypertrophy such as AKT1, CAMK, GRK5, GSK3β, MLCK, PKC, PKD2, AMPK, ROCK2, p70S6K, SGK1were evaluated. Polymyxin B possesses a potent G protein related kinase 5 (GKR5) inhibitory activity with IC50 value of 1.1 μM, and has an ATP non-competitive inhibitory mode. Taken together, these results indicate that polymyxin B alleviates Ang II-induced stress fiber formation and cellular hypertrophy, and propose that one mechanism underlying these effects involves inhibition of the GRK5 pathway.

Influence of Driver’s Career and Secondary Cognitive Task on Visual Search Behavior in Driving: A Dual-Task Paradigm  [PDF]
Hye-In Lee, Seungha Park, Jongil Lim, Seung Ho Chang, Jung-Hyun Ji, Seungmin Lee, Jihye Lee
Advances in Physical Education (APE) , 2015, DOI: 10.4236/ape.2015.54029
Abstract: The purpose of this study was to investigate the effect of driving career and secondary cognitive task on dual-tasking performances and visual search behavior. Twenty male participants were grouped in the following two groups: the experienced group and the novice group. All participants were asked to drive at a speed of 120 km/h while keeping to a lane on the highway and engaging with the following three levels of secondary cognitive task: no cognitive task, easy level, and hard level. The results showed significantly lower correct response rates in the dual task condition (driving + cognitive task) than in the driving only task condition. Novice drivers showed greater decrements in cognitive task performance, particularly in the dual task condition, as compared to the experienced drivers. The total fixation duration decreased as the level of the secondary task increased in difficulty. Experienced drivers showed significantly longer fixation duration on the far-area of the road, and also on specific areas, whereas novice drivers fixated longer on the near-area of the road. In conclusion, we suggest that the importance of perceptual skills in driving should be emphasized and effective training methods need to be applied, especially among high-risk drivers.
An Experiment on Power Properties in a Small-Scaled Wind Turbine Generator  [PDF]
Jee-Ho Kim, Hyun-Dai Yang, Kyu-Jin Lee, Sung-Do Song, Sung-Hoon Park, Joong-Ho Shin
Journal of Power and Energy Engineering (JPEE) , 2013, DOI: 10.4236/jpee.2013.17002

This study configures a simple wind tunnel using a blower for generating wind energy, which is equivalent to natural wind, and a test system that measures properties of power. Also, the mechanical and electrical power in a small-scaled wind turbine are empirically measured to analyze the relationship between the mechanical and electrical power.

An Efficient Method of Vibration Diagnostics For Rotating Machinery Using a Decision Tree
Bo Suk Yang,Chul Hyun Park,Ho Jong Kim
International Journal of Rotating Machinery , 2000, DOI: 10.1155/s1023621x00000038
Abstract: This paper describes an efficient method to automatize vibration diagnosis for rotating machinery using a decision tree, which is applicable to vibration diagnosis expert system. Decision tree is a widely known formalism for expressing classification knowledge and has been used successfully in many diverse areas such as character recognition, medical diagnosis, and expert systems, etc. In order to build a decision tree for vibration diagnosis, we have to define classes and attributes. A set of cases based on past experiences is also needed. This training set is inducted using a result-cause matrix newly developed in the present work instead of using a conventionally implemented cause-result matrix. This method was applied to diagnostics for various cases taken from published work. It is found that the present method predicts causes of the abnormal vibration for test cases with high reliability.
Pseudocapacitive Effects of N-Doped Carbon Nanotube Electrodes in Supercapacitors
Young Soo Yun,Hyun Ho Park,Hyoung-Joon Jin
Materials , 2012, DOI: 10.3390/ma5071258
Abstract: Nitrogen- and micropore-containing carbon nanotubes (NMCNTs) were prepared by carbonization of nitrogen-enriched, polymer-coated carbon nanotubes (CNTs), and the electrochemical performances of the NMCNTs with different heteroatom contents were investigated. NMCNTs-700 containing 9.1 wt% nitrogen atoms had a capacitance of 190.8 F/g, which was much higher than that of pristine CNTs (48.4 F/g), despite the similar surface area of the two CNTs, and was also higher than that of activated CNTs (151.7 F/g) with a surface area of 778 m 2/g and a nitrogen atom content of 1.2 wt%. These results showed that pseudocapacitive effects play an important role in the electrochemical performance of supercapacitor electrodes.
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