• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.66-66
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• 2003

In skeletal muscle cells, depolarization of the transverse tubules (T-tubules) results in Ca$\^$2+/ release from the sarcoplasmic reticulum (SR), leading to elevated cytoplasmic Ca$\^$2+/ and muscle contraction. This process has been known as excitation-contraction coupling (E-C coupling). Several proteins, such as the ryanodine receptor (RyR), triadin, junctin, and calsequestrin (CSQ), have been identified to be involved in the Ca$\^$2＋/ release process. However, the molecular interactions between the SR proteins have not been resolved. In the present study, the mechanisms of interaction between RyRl and triadin have been studied by in vitro protein binding and $\^$45/Ca$\^$2+/ overlay assays. Our data demonstrate that the intraluminal loop II of RyR1 binds to triadin in Ca$\^$2+/-independent manner. Moreover, we could not find any Ca$\^$2+/ binding sites in the loop II region. GST-pull down assay revealed that a KEKE motif of triadin, which was previously identified as a CSQ binding site (Kobayasi et al.,2000 JBC) was also a binding site for RyR1. Our results suggest that the intraluminal loop II of RyR could participate in the RyR-mediated Ca$\^$2+/ release process by offering a direct binding site to luminal triadin.

• Molecules and Cells
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• v.39 no.2
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• pp.149-155
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• 2016

In the heart, excitation-contraction (E-C) coupling is mediated by $Ca^{2+}$ release from sarcoplasmic reticulum (SR) through the interactions of proteins forming the $Ca^{2+}$ release unit (CRU). Among them, calsequestrin (CSQ) and histidine-rich $Ca^{2+}$ binding protein (HRC) are known to bind the charged luminal region of triadin (TRN) and thus directly or indirectly regulate ryanodine receptor 2 (RyR2) activity. However, the mechanisms of CSQ and HRC mediated regulation of RyR2 activity through TRN have remained unclear. We first examined the minimal KEKE motif of TRN involved in the interactions with CSQ2, HRC and RyR2 using TRN deletion mutants and in vitro binding assays. The results showed that CSQ2, HRC and RyR2 share the same KEKE motif region on the distal part of TRN (aa 202-231). Second, in vitro binding assays were conducted to examine the $Ca^{2+}$ dependence of protein-protein interactions (PPI). The results showed that TRN-HRC interaction had a bell-shaped $Ca^{2+}$ dependence, which peaked at pCa4, whereas TRN-CSQ2 or TRN-RyR2 interaction did not show such $Ca^{2+}$ dependence pattern. Third, competitive binding was conducted to examine whether CSQ2, HRC, or RyR2 affects the TRN-HRC or TRN-CSQ2 binding at pCa4. Among them, only CSQ2 or RyR2 competitively inhibited TRN-HRC binding, suggesting that HRC can confer functional refractoriness to CRU, which could be beneficial for reloading of $Ca^{2+}$ into SR at intermediate $Ca^{2+}$ concentrations.

• Molecules and Cells
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• v.22 no.3
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• pp.328-335
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• 2006

Imperatoxin A ($IpTx_a$), a 3.7 kDa peptide from the African scorpion Pandinus imperator, is an agonist of the skeletal muscle ryanodine receptor (RyR1). In order to study the structure of the toxin and its effect on RyR1, $IpTx_a$ cDNA was PCR-amplified using 3 pairs of primers, and the toxin was expressed in E. coli. The toxin was further purified by chromatography, and various point mutants in which basic amino acids were substituted by alanine were prepared by site-directed mutagenesis. Studies of single channel properties by the planar lipid bilayer method showed that the recombinant $IpTx_a$ was identical to the synthetic $IpTx_a$ with respect to high-performance liquid chromatography mobility, amino acid composition and specific effects on RyR1. Mutations of certain basic amino acids ($Lys^{19}$, $Arg^{23}$, and $Arg^{33}$) dramatically reduced the capacity of the peptide to activate RyRs. A subconductance state predominated when $Lys^8$ was substituted with alanine. These results suggest that some basic amino acid residues in $IpTx_a$ are important for activation of RyR1, and that $Lys^8$ plays an important role in regulating the gating mode of RyR1.

• The Korean Journal of Pharmacology
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• v.32 no.1
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• pp.57-66
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• 1996

To investigate properties of Ca-release channel in the reptile skeletal muscle, electrophoretical analysis, purification of RyR, $[^3H]ryanodine$binding study, and $^{45}Ca-release$ were carried out in the SR vesicles prepared from the snake skeletal muscle. The snake SR vesicle has the single high molecular weight protein band on SDS-PAGE, and its mobility was similar with that of rat skeletal SR vesicles. The high molecular weight band on SDS-PACE was found in the $[^3H]ryanodine$ peak fractions $(Fr_{5-7})$ obtained from the purification step of the RyR. Maximal binding site and Kd of the snake SR RyR were 6.36 pmole/mg protein and 17.62 nM, respectively. Specific binding of $[^3H]ryanodine$ was significantly increased by calcium and AMP (P<0.05), but not or slightly inhibited by tetracaine, ruthenium red (5.4%), or $MgCl_2$ (21%). $^{45}Ca-release$ from the SR vesicles loaded passively was significantly increased by the low concentration of calcium $(1{\sim}10{\mu}M)$ and AMP (5 mM)(P<0.05), but significantly decreased by the high concentration $(300{\mu}M)$ of calcium, tetracaine (1 mM), ruthenium red $(10{\mu}M)$, and $MgCl_2$ (2 mM)(P <0.05). From the above results, it is suggested that snake SR vesicles also have the RyR showing the similar properties to those of mammalian skeletal RyR with the exceptions of no or slight inhibition of $[^3H]ryanodine-binding$ by tetracaine, ruthenium red, or $MgCl_2$.

• Journal of Ginseng Research
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• v.20 no.3
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• pp.274-283
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• 1996

In this study, the effects of red ginseng components [ginsenosides (total saponins and $Rg_1$) on the function of ryanodine receptor (RyR) -$Ca^{2+}$ release channel complex protein (named as RyR or $Ca^{2+}$ channel), a membrane protein in sarcoplasmic reticulum (SR) of rabbit skeletal muscle were examined at the SR vesicle's level and the molecular levels with Chaps-solubilized and purified $Ca^{2+}$ channel protein and with reconstituted proteoliposomes by dialysis. The results were as follows. 1. The binding of ryanodine known as inhibitor of muscle contraction to the RyR was decreased at the whole range of concentration ($10^2$~$10^7$%) by these two ginseng components. In heavy SR vesicles, Chaps-solubilized and purified $Ca^{2+}$ channel protein, and reconstituted vesicles, its maximal inhibition by total saponins was shown at the concentration of $10^3$, $10^3$%, and $10^5$% respectively, and by gin- senoside $Rg_1}$) each was $10^3$%, $10^3$%, and $10^4$%. 2. The release of $Ca^{2+}$ ion through $Ca^{2+}$ channel in heavy SR vesicles and reconstituted proteoliposomes was increased as a whole by these two ginseng components, and particularly maximal release by both of them was shown at the range of $10^4$~$10^6$%. These results were seemed to be caused by conformational change of $Ca^{2+}$ release channel protein (RyR) by red ginseng components [ginsenosides (total saponins and $Rg_1}$).

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.229-230
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• 2015

The results of spectral studies of the CTTS type young star RY Tau with spectrograms of the ultraviolet and the visual ranges are presented. We show the first detection of periodic variability of the emission line intensities in UV and visual ranges with a period of 23 days.

• Korean journal of applied entomology
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• v.55 no.4
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• pp.413-419
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• 2016

Ryanodine receptors (RyRs) regulate the contractions of insect muscles by altering intracellular $Ca^{2+}$ concentration and are the targets of chlorantraniliprole. Recently, a chlorantraniliprole-resistant strain was reported in the diamondback moth Plutella xylostella by obtaining point mutations on the RyRs. In the present study, we established two resistant strains from Drosophila melanogaster, which were treated with low or high concentrations of chlorantraniliprole, and their resistance levels were determined on the basis of contact and ingestion toxicities. Compared with the control strain, the two resistant strains did not show any significant differences in contact toxicity. However, they showed significantly increased resistance ratios in ingestion toxicity than that by the control strain. The low and high concentration resistant strains exhibited 2.1- and 8.1-fold increased resistance ratios, respectively, compared with that by the control strain. Moreover, we found that the resistant strains had altered expression levels of RyRs and more enhanced Acetylcholinesterase and Glutathione-S-transferase activities than that by the non-selected strain. These results suggested that the resistance development of chlorantraniliprole in the two strains might be mediated by the activation of detoxification pathways in D. melanogaster.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.202-210
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• 2020

This study investigated the optimal levels of stand density control considering the stability of Larix kaempferi stands. A stand density management diagram was developed from 259 sample plots. Based on these data, we determined an optimal level of the stand density control by identifying the relationship between the relative yield index (Ry) and height-to-diameter ratio. The estimated r-square (R²) of the stand density management diagram is 0.600. The analysis of the relationship between Ry and the slender tree incidence showed that when the stand density exceeded a certain threshold and the ratio of slender trees rapidly increased. The critical value of Ry was 0.63. The results of this study are expected to contribute to the establishment of stand management strategies that can reduce damage from natural causes, such as wind and snow, and to develop stand practice systems for the improved productivity of commercial forests.

• YAKHAK HOEJI
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• v.48 no.6
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• pp.352-357
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• 2004

Atrial myocytes have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with L-type $Ca^{2+}$channels (DHPRS) and those a t the cell interior not associated with DHPRs. $Ca^{2+}$ current ($I_{ca}$) directly gates peripheral RyRs on action potential and the subsequent peripheral $Ca^{2+}$ release propagates into the center of atrial myocytes. The mechanisms that regulate the $Ca^{2+}$+ propagation wave remain Poorly understood. Using 2-D confocal$Ca^{2+}$ imaging, we examined the role of inositol 1,4,5-trisphosphate receptor (IP $_3R$) and mitochondria on ($I_{ca}$)- gated local $Ca^{2+}$ signaling in rat atrial myocytes. Blockade of IP $_3R$ by xestospongin C (XeC) partially suppressed the magnitudes of I ca-gated central and peripheral $Ca^{2+}$ releases with no effect on $I_{ca}$. Mitochondrial staining revealed that mitochondria were aligned with ${\thickapprox}2-{\mu}m$ separations in the entire cytoplasm of ventricular and atrial myocytes. Membrane depolarization induced rapid mitochondrial $Ca^{2+}$ rise and decay in the cell periphery with slower rise in the center, suggesting that mitochondria may immediately uptake cytosolic $Ca^{2+}$, released from the peripheral SR on depolarization, and re-release the $Ca^{2+}$ into the cytosol to activate neighboring central RyRs. Our data suggest that the activation of IP $_3R$ and mitochondrial $Ca^{2+}$ handing on action potential may serve as a cofactor for the $Ca^{2+}$ propagation from the DHPR-coupled RyRs to the DHPR-uncoupled RyRs with large gaps between them.

• Korean journal of applied entomology
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• v.35 no.4
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• pp.297-301
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• 1996

This test has been carried out to evaluate the effect of temperature on the growth of the insecticide susceptible strain, URY-O nomal genotype and insecticide resistant strain, O-RT abnormal genotype, and ABURABI nomal genotype. The nymphal periods were not significantly different between URY-O and O-RY strains at $25^{\circ}C$. At $30^{\circ}C$, susceptible strain URY-O could give birth to offsprings almost nomally, while resistant strain O-RY could not produce any offspring for 20 days which results in nymphal death. The numbers of offsprings of strain URY-O and strain ABURABI were not different between $25^{\circ}C\;and\;28^{\circ}C$, but strain O-RY, when it was reared at $28^{\circ}C$, could produce offsprings only 10% of those at $25^{\circ}C$. Body weight of strain URY-O and strain ABURABI were 0.22mg/female and 0.27mg/female, respectively at $28^{\circ}C$, however that of O-RY was only 0.16mg/female, showing considerable difference between normal and abnormal genotype. Substrain O-RY(+) which has high esterase activity showed poor reproduction ability(0.8 progenies per $G_{1}$ individual than substrain O-RY(-) (3.4 progenies per $G_{1}$ individual) which has low esterase activity at $28^{\circ}C$