Minkyu Park | Konkuk University (original) (raw)

Papers by Minkyu Park

The Journal of Neuroscience, 1998

Transient ischemia leads to changes in synaptic efficacy and results in selective neuronal damage... more Transient ischemia leads to changes in synaptic efficacy and results in selective neuronal damage during the postischemic phase, although the mechanisms are not fully understood. The protein composition and ultrastructure of postsynaptic densities (PSDs) were studied by using a rat transient ischemic model. We found that a brief ischemic episode induced a marked accumulation in PSDs of the protein assembly ATPases,N-ethylmaleimide-sensitive fusion protein, and heat–shock cognate protein-70 as well as the BDNF receptor (trkB) and protein kinases, as determined by protein microsequencing. The changes in PSD composition were accompanied by a 2.5-fold increase in the yield of PSD protein relative to controls. Biochemical modification of PSDs correlated well with an increase in PSD thickness observedin vivoby electron microscopy. We conclude that a brief ischemic episode modifies the molecular composition and ultrastructure of synapses by assembly of proteins to the postsynaptic density,...

Journal of Biological Chemistry, 2000

We isolated styelin D, a 32-residue, C-terminally amidated antimicrobial peptide, from the blood ... more We isolated styelin D, a 32-residue, C-terminally amidated antimicrobial peptide, from the blood cells (hemocytes) of the solitary ascidian, Styela clava. Styelin D had remarkably extensive post-translational modifications, containing two novel amino acids, dihydroxyarginine and dihydroxylysine, and two distinctly unusual ones, 6-bromotryptophan and 3,4-dihydroxyphenylalanine. In addition, the peptide exhibited microheterogeneity because of differential mono-and dihydroxylation of several lysine residues. The primary sequence of one variant was: GW

Virology, 1999

All poxviruses studied encode a type 1B topoisomerase that introduces transient nicks into DNA an... more All poxviruses studied encode a type 1B topoisomerase that introduces transient nicks into DNA and thereby relaxes DNA supercoils. Here we present a study of the protein domains of the topoisomerase of the poxvirus molluscum contagiosum (MCV), which allows us to specify DNA contacts made by different domains. Partial proteolysis of the enzyme revealed two stable domains separated by a protease-sensitive linker. A fragment encoding the linker and carboxyl-terminal domain (residues 82-323) was overexpressed in Escherichia coli and purified. MCV topoisomerase (MCV-TOP)(82-323) could relax supercoiled plasmids in vitro, albeit with a slower rate than the wild-type enzyme. MCV-TOP(82-323) was sensitive to sequences in the favored 5Ј-(T/C)CCTT-3Ј recognition site and also flanking DNA, indicating that some of the sequencespecific contacts are made by residues 82-323. Assays of initial binding and covalent catalysis by MCV-TOP(82-323) identified the contacts flanking the 5Ј-CCCTT-3Ј sequence at ϩ10, ϩ9, Ϫ2, and Ϫ3 to be important. Tests with substrates containing a 5-bridging phosphorothiolate that trap the cleaved complex revealed that correct contacts to the flanking sequences were important in the initial cleavage step. MCV-TOP(82-323) differed from the full-length protein in showing reduced sensitivity to mutations at a position within the 5Ј-(T/C)CCTT-3Ј recognition site, consistent with a model in which the amino-terminal domain contacts this region. These findings provide insight into the division of labor within the MCV-TOP enzyme.

Regulatory Peptides, 1997

Perchlike fish are a vast group of advanced teleosts. The species examined to date have three for... more Perchlike fish are a vast group of advanced teleosts. The species examined to date have three forms of gonadotropin-releasing hormone (GnRH) within a single species, but the origin of the third GnRH peptide is unknown. In this study, the primary structure of three GnRH peptides is determined from the brain of the pacu, Piaractus mesopotamicus, an example of a teleost that is less advanced than the perchlike fish. The GnRH was purified from pacu brain extracts using high-performance liquid chromatography (HPLC) and radioimmunoassay (RIA). The three forms identified by chemical sequencing and mass spectrometry are sea bream GnRH (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Ser-Pro-Gly-NH , 1113.4 Da); chicken GnRH-II (pGlu-His-Trp-Ser-His-Gly-Trp-Tyr-Pro-Gly-NH , 2 2 1236.6 Da); and salmon GnRH (pGlu-His-Trp-Ser-Tyr-Gly-Trp-Leu-Pro-Gly-NH , 1212.3 Da). In addition, the number of forms 2 of GnRH in the brains of male and female fish was determined separately. The same three forms of GnRH were present in the brains of both sexes as determined by antisera cross-reactivity and elution position from the HPLC column. The results indicate that the pacu brain has the identical forms of GnRH identified in perchlike fish and hence, the origin of three forms occurred earlier in evolution than previously thought.

Molecular Biology of the Cell, 2000

The study of the nuclear pore in vertebrates would benefit from a strategy to directly identify n... more The study of the nuclear pore in vertebrates would benefit from a strategy to directly identify new nucleoporins and interactions between those nucleoporins. We have developed a novel two-step “organelle trap” assay involving affinity selection and in vitro pore assembly. In the first step, soluble proteins derived from Xenopusegg extracts are applied to a column containing a ligand of interest. The bound proteins are then tagged by biotinylation and eluted. In the second step, potential nucleoporins are selected for by virtue of their ability to assemble into annulate lamellae, a cytoplasmic mimic of nuclear pores. The incorporated proteins are then recognized by their biotin tag. Here we use the lectin wheat germ agglutinin (WGA) as ligand; WGA inhibits nuclear transport and has been shown to directly bind three known nucleoporins from Xenopus extract, Nup62, Nup98, and Nup214, all of which containN-acetylglucosamine residues. Under reduced-stringency conditions, three additional ...

Lipids, 1998

In studies of bovine plasma lipoproteins, apolipoprotein E (apoE) was not found associated with α... more In studies of bovine plasma lipoproteins, apolipoprotein E (apoE) was not found associated with α-lipoproteins isolated over a broad range of densities. However, studies of cerebrospinal fluid (CSF) lipoproteins from other mammals have shown that apoE is a major apolipoprotein associated with high density lipoprotein, a fact that prompted us to determine if this were also the case in bovine CSF. CSF samples were obtained from animals with a surgically implanted catheter. Most analyzed samples were obtained from cows at various stages of the postpartum period; however, a few samples also were obtained at term or during pregnancy. Analyses of isolated ultracentrifugal fractions by polyacrylamide gel electrophoresis revealed the presence of two apo, with the expected molecular weights for apoE and apoA-I. By using both matrix-assisted laser desorption mass spectrometry and microsequencing techniques, we demonstrated that these apo are indeed apoE and apoA-I.

Journal of Biological Chemistry, 2004

FEBS Letters, 1997

The primary structure of two forms of gonadotropin releasing hormone (GnRH) from tunicate {Chelyo... more The primary structure of two forms of gonadotropin releasing hormone (GnRH) from tunicate {Chelyosoma productuni) have been determined based on mass spectrometric and chemical sequence analyses. The peptides, tunicate GnRH-I and-II, contain features unprecedented in vertebrate GnRH. Tunicate GnRH-I contains a putative salt bridge between Asp 0 and Lys 8. A GnRH analog containing a lactam bridge between Asp 5 and Lys 8 was found to increase release of estradiol compared with that of the native tunicate GnRH-I and-II. Tunicate GnRH-I I contains a cysteine residue and was isolated as a dimeric peptide. These motifs suggest that the conformation plays an important role in receptor activation.

Biology of Reproduction, 2002

Multiple forms of GnRH within individual brains may have different functions. However, some verte... more Multiple forms of GnRH within individual brains may have different functions. However, some vertebrates such as salmonids continue to reproduce even though they have lost or do not express 1 of the 3 forms of GnRH found in most other teleosts. We examined a basal salmonid, lake whitefish, to determine the mechanism by which a reduction in the number of GnRH forms occurs. We identified for the first time 3 distinct GnRHs in a salmonid. One form is novel and is designated whitefish GnRH. The primary structure is pGlu-His-Trp-Ser-Tyr-Gly-Met-Asn-Pro-Gly-NH 2. HPLC and RIA were used for purification followed by Edman degradation for sequence determination. Mass spectroscopy was used to confirm the sequence and amidation of the peptide. The other 2 forms, salmon GnRH and chicken GnRH-II, are identical to the 2 forms found in salmon, which evolved later than whitefish. Synthetic whitefish GnRH is biologically active, as it increased mRNA expression of growth hormone and the ␣-subunit for LH and thyroid-stimulating hormone in dispersed fish pituitary cells. Our data support the hypothesis that the ancestral salmonid had a third GnRH form when the genome doubled (tetraploidization), but the third form was lost later in some salmonids due to chromosomal rearrangements. We suggest that the salmon GnRH form compensated for the loss of the third form.

Biochemical and Biophysical Research Communications, 2007

The main objective of this study was to investigate the biological function of β amyloid precurso... more The main objective of this study was to investigate the biological function of β amyloid precursor protein (APP), in particular its nerve growth factor-like activity. We hypothesize that the extracellular domain containing the sequence RERMS, amino acids 328-332 of APP 695 , represents the active site for this function. Binding assays using peptide fragments of this domain have demonstrated specific and saturable binding to the cell surface with affinity in the low nanomolar range. This induced our quest for an APP-specific receptor. We chose different peptide fragments of the RERMS domain as ligands and displacing agents on affinity columns to purify APP binding molecules. Amino acid microsequencing yielded partial sequences of serum albumin, actin, two novel proteins of 41 and 63 kDa and human Collapsin Response Mediator Protein-2 (hCRMP-2). Because both APP and hCRMP-2 promote neuronal outgrowth and use a common signaling pathway, APP could be acting through a semaphorin receptor as well.

TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, Jan 28, 2016

Using fine mapping techniques, the genomic region co-segregating with Restorer - of - fertility (... more Using fine mapping techniques, the genomic region co-segregating with Restorer - of - fertility ( Rf ) in pepper was delimited to a region of 821 kb in length. A PPR gene in this region, CaPPR6 , was identified as a strong candidate for Rf based on expression pattern and characteristics of encoding sequence. Cytoplasmic-genic male sterility (CGMS) has been used for the efficient production of hybrid seeds in peppers (Capsicum annuum L.). Although the mitochondrial candidate genes that might be responsible for cytoplasmic male sterility (CMS) have been identified, the nuclear Restorer-of-fertility (Rf) gene has not been isolated. To identify the genomic region co-segregating with Rf in pepper, we performed fine mapping using an Rf-segregating population consisting of 1068 F2 individuals, based on BSA-AFLP and a comparative mapping approach. Through six cycles of chromosome walking, the co-segregating region harboring the Rf locus was delimited to be within 821 kb of sequence. Predict...

usenix.org

Recent malware often collects sensitive information from third-party applications with an illegal... more Recent malware often collects sensitive information from third-party applications with an illegally escalated privilege to the system level (the highest level) on the Android platform. An attack to obtain root-level privilege in an Android environment can pose a ...

2009 International Conference on Embedded Software and Systems, 2009

ABSTRACT Minimizing energy consumption with guaranteeing real-time constraints in low-power embed... more ABSTRACT Minimizing energy consumption with guaranteeing real-time constraints in low-power embedded systems is gaining more importance as real-time applications become more widely used in embedded systems. Dynamic voltage scaling is a technique to reduce energy consumption by lowering supply voltage. However, lowering supply voltage may interfere with scheduling algorithms, so that tasks may not be successfully scheduled. In this paper, we formulate the problem of minimizing energy consumption for pre-scheduling as an optimization problem, and show that the problem is a nonlinear convex optimization with linear constraints which can be solved by sequential quadratic programming. By solving the problem, we can obtain the optimal supply voltage and successful scheduling of all tasks is guaranteed.

2008 International Conference on Information Science and Security (ICISS 2008), 2008

Since many people consume multimedia content (music, movie etc.) on mobile devices, mobile DRM be... more Since many people consume multimedia content (music, movie etc.) on mobile devices, mobile DRM becomes important, which controls digital content usage under wireless environment. In a typical DRM model, a block cipher is usually used to encrypt multimedia content because of its reasonable security and performance. However, encrypting multimedia content using a block cipher in mobile environment requires much computation

TheScientificWorldJournal, 2014

Authenticated key exchange protocols are of fundamental importance in securing communications and... more Authenticated key exchange protocols are of fundamental importance in securing communications and are now extensively deployed for use in various real-world network applications. In this work, we reveal major previously unpublished security vulnerabilities in the password-based authenticated three-party key exchange protocol according to Lee and Hwang (2010): (1) the Lee-Hwang protocol is susceptible to a man-in-the-middle attack and thus fails to achieve implicit key authentication; (2) the protocol cannot protect clients' passwords against an offline dictionary attack; and (3) the indistinguishability-based security of the protocol can be easily broken even in the presence of a passive adversary. We also propose an improved password-based authenticated three-party key exchange protocol that addresses the security vulnerabilities identified in the Lee-Hwang protocol.

Lecture Notes in Computer Science, 2009

Group key exchange protocols allow a group of parties communicating over a public network to come... more Group key exchange protocols allow a group of parties communicating over a public network to come up with a common secret key called a session key. Due to their critical role in building secure multicast channels, a number of group key exchange protocols have been suggested over the years for a variety of settings. Among these is the so-called EKE-M protocol proposed by Byun and Lee for password-based group key exchange in the different password authentication model, where group members are assumed to hold an individual password rather than a common password. While the announcement of the EKE-M protocol was essential in the light of the practical significance of the different password authentication model, Tang and Chen showed that the EKE-M protocol itself suffers from an undetectable on-line dictionary attack. Given Tang and Chen’s attack, Byun et al. have recently suggested a modification to the EKE-M protocol and claimed that their modification makes EKE-M resistant to the attack. However, the claim turned out to be untrue. In the current paper, we demonstrate this by showing that Byun et al.’s modified EKE-M is still vulnerable to an undetectable on-line dictionary attack. Besides reporting our attack, we also figure out what has gone wrong with Byun et al.’s modification and how to fix it.

Lecture Notes in Computer Science

A cryptographic file system is the representative way of assuring confidentiality of files in ope... more A cryptographic file system is the representative way of assuring confidentiality of files in operating systems. For secure embedded operating systems, the cryptographic file system could be a practical technique. In general, cryptographic file systems are implemented using a stackable file system or a device driver. These two mechanisms can provide user transparent encryption/decryption of cryptographic file systems. But these mechanisms sometimes encrypt or decrypt data redundantly or unnecessarily. Embedded systems with a low speed CPU and flash storage are more affected by the problems than general systems. We addressed the above mentioned problems by applying an encryption algorithm on buffer caches and enabling one buffer cache to have both encrypted and decrypted data together. Experimental results show that the proposed mechanisms reduce the redundant or unnecessary operations and it can improve the performance of cryptographic file systems.

Proceedings of the 2013 Research in Adaptive and Convergent Systems on - RACS '13, 2013

ABSTRACT By measuring similarity of programs, we can determine whether someone illegally copies a... more ABSTRACT By measuring similarity of programs, we can determine whether someone illegally copies a program from another program or not. If the similarity is significantly high, it means that a program is a copy of the other. This paper proposes three techniques to measure similarity of the Dalvik executable codes (DEXs) in the Android application Packages (APKs). Firstly, we decompile the DEXs of candidate applications into Java sources and compute the similarity between the decompiled sources. Secondly, candidate DEXs are disassembled and the similarities between disassembled codes are measured. Finally, we extract k-gram based software birthmark form the dissembled codes and calculate the similarity of sample DEXs by comparing the extracted birthmarks. We perform several experiments to identify effects of the three techniques. With the analysis of the experimental results, the advantages and disadvantages of each technique are discussed.

2013 Seventh International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing, 2013

ABSTRACT A software birthmark is unique and native characteristics of software, and thus can be u... more ABSTRACT A software birthmark is unique and native characteristics of software, and thus can be used to detect the theft of software. We propose a new static software birthmark for programs on Microsoft Windows which have Portable Executable (PE) format. These programs use different Dynamic Link Libraries (DLLs) and Application Program Interfaces (APIs) while they are executing. The number and names of the used DLLs and APIs are unique to each program. The proposed birthmark is based on these numbers and names. This information can be obtained from the Import Address Table (IAT), which is part of the PE file. By inspecting the proposed birthmark, we can identify certain software and detect pirated software. To evaluate the effectiveness of the proposed birthmark, we inspect and compare several applications of different kinds. The experimental results show that the proposed birthmark can identify Windows applications, leading to the prevention of an illegal distribution of copyrighted software.