• Journal of Biosystems Engineering
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• 제38권2호
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• pp.129-137
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• 2013

Purpose: Modeling has been used for elucidating the mechanism of complex biosystems. In spite of importance and uniqueness of adolescent calcium (Ca) metabolism characterized by a threshold Ca intake, its regulatory mechanism has not been covered and even not proposed. Hence, this study aims at model-based proposing potential mechanisms regulating adolescent Ca metabolism. Methods: Two different hypothetic mechanisms were proposed. The main mechanism is conceived based on Ca-protein binding which induces renal Ca filtration, while additional mechanism assumed that active renal Ca re-absorption regulated Ca metabolism in adolescents. Mathematical models were developed to represent the proposed mechanism and simulated them whether they could produce adolescent Ca profiles in serum and urine. Results: Simulation showed that both mechanisms resulted in the unique behavior of Ca metabolism in adolescents. Based on the simulation insulin-like growth factor-1 (IGF-1) is suggested as a potential regulator because it is related to both growth, a remarkable characteristic of adolescence, and Ca metabolism including absorption and bone accretion. Then, descriptive modeling is employed to conceptualize the hypothesized mechanisms governing adolescent Ca metabolism. Conclusions: This study demonstrated that modeling is a powerful tool for elucidating an unknown mechanism by simulating potential regulatory mechanisms in adolescent Ca metabolism. It is expected that various analytic applications would be plausible in the study of biosystems, particularly with combination of experimental and modeling approaches.

• Journal of Microbiology
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• 제37권1호
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• pp.21-26
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• 1999

Two novel calcium-binding proteins, named CAB-I and CAB-II, have been isolated from Streptomyces coelicolor. Purification of the calcium-binding proteins involved heat treatment, fractionation with ammonium sulfate, acid treatment, anion exchange and hydrophobic interaction column chromatography, FPLC gel filtration, and preparative isoelectric focusing. A chelex competitive assay and 45Ca autoradiography verified the calcium-binding ability of the proteins. The major band CAB-II has an apparent molecular weight of 26,000 determined by SDS-polyacrylamide gel electrophoresis and 340,000 determined by gel filtration. The isoelectric point of this molecule showed the acidic nature of the molecule. N-terminal amino acid sequence analysis shows homology to rat Ca2+/calmodulin-dependent protein kinase-II (CAB-II) and yeast phosphoprotein phosphatase (CAB-I).

• 대한물리치료과학회지
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• 제11권1호
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• pp.20-27
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• 2004

It is widely accepted that smooth muscle contraction is triggered by intracellular $Ca^{2+}$ ($[Ca^{2+}]_i$) released from intracellular $Ca^{2+}$ stores such as sarcoplasmic reticulum (SR) and from the extracellular space, The increased $[Ca^{2+}]_i$ can phosphorylate the 20-kDa myosin light chain ($MLC_{20}$) by activating MLC kinase (MLCK), and this initiates smooth muscle contraction. In addition to the $[Ca^{2+}]_i$-MLCK-tension pathway, a number of intracellular signal molecules, including mitogen-activated protein kinase (MAPK), protein kinase C (PKC), phosphatidylinositol 3-kinase (PI3K), and Rho-associated coiled coil-forming protein kinase (ROCK), play important roles in the regulation of smooth muscle contraction. However, the mechanisms regulating contraction of caldesmon (CaD), actin-binding protein, are not entirely elucidated in the presence of $Ca^{2+}$. It is known that CaD tightly interacts with actin and inhibits actomyosin ATPase activity. Therefore, the purpose of the present study was to investigate the roles of $Ca^{2+}$-dependent CaD in smooth muscle contraction. Endothelin-1 (ET-1), G-protein coupled receptor agonist and vasoconstrictor, increased both vascular smooth contraction and phosphorylation of CaD in the presence of $Ca^{2+}$. These results suggest that ET-1 induces contraction and phosphorylation of CaD in rat aortic smooth muscle, which may he mediated by the increase of $[Ca^{2+}]_i$.

• 생명과학회지
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• 제17권9호통권89호
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• pp.1177-1181
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• 2007

칼모둘린은 칼슘과 결합하는 센서로써 다양한 칼모둘린 결합 단백질들과의 상호 작용을 통하여 세포 내에서 여러가지 기능을 조절한다. 진핵 생물들은 많은 종류의 칼모둘린 결합 단백질을 가지고 있기 때문에 이러한 단백질들의 분리와 특성 규명이 중요하다. 이미 여러 가지 방법들을 이용하여 칼모둘린 결합 단백질들이 분리되었고 이미 알려진 단백질의 구조적인 유사성을 토대로 더 많은 단백질들이 예측되었다. 우리는 애기장대에서 칼모둘린 결합 단백질의 분리와 특성 규명을 위해 형광 단백질과 융합된 칼모둘린 과발현 형질 전환체를 제조하여 공촛점 현미경과 Western blot 을 이용하여 과발현 형질 전환체를 선별하였다. 또한 형질 전환체 내의 칼모둘린이 칼모둘린 결합 단백질과 상호 작용함을 pull-down 분석을 통해서 확인하였다. 이러한 결과들을 토대로 칼모둘린 과발현 형질 전환체를 이용하여, 칼모둘린과 상호 작용하는 여러 가지 칼모둘린 결합 단백질들을 분리할 수 있을 것으로 기대된다.

• 생명과학회지
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• 제4권2호
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• pp.50-59
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• 1994

신호전달과정의 연구는 calcium이 messenger로서 작용한다고 밝혀진 후로 식물에서 $Ca^{++}$ -messenger system에 대한 생화학적 및 분자생물학적 분야에서의 연구는 급속하게 발전하게 되었다. 식물세포에서 calcium 이온들의 많은 작용은 EF hand family로서 알려진 calcium binding protein에 의해서 조절된다. Calmodulin (CaM)은 highy conserve 되어 있으며, 4개의 calcium binding domain을 가진 ubiquitous한 단백질이다. 본 연구는 calmodulin 유전자의 발현에 미치는 calcium, EGTA, calcium ionophore 및 calmodulin antagonist의 영향과 또한 외부신호(light, wounding), chemical 및 auxin 등의 영향을 reporter화 유전자의 분석에 의해서 CaM유전자의 발현기작을 규명하고자 하였고, 또한 calmodulin 유전자의 organ-specific 발현 및 calmodulin의 새로운 생리적인 기능도 연구하고자 하였다.

• 대한약리학회지
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• 제18권2호
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• pp.33-44
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• 1982

전해질농도(電解質濃度)를 달리하고 morphine, naloxone 또는 morphine+naloxone을 가(加)하거나 가(加)하지 않은 modified Krebs-Henseleit bicarbonate buffer용액(溶液)에 흰쥐의 뇌절편(腦切片)을 incubate하여 저온처리(低溫處理)와 media내(內) 전해질조성(電解質組成)이 $(^3H)-morphine$의 saturable binding에 미치는 영향(影響)을 관찰(觀察)하여 다음과 같은 성적(成績)을 얻었다. 1) 저온처리(低溫處理)는 $(^3H)-morphine$의 saturable binding을 현저(顯著)히 증가(增加)시켰고, maximal saturable binding은 증가(增加)시키나 $K_D$치(値)에는 영향(影響)을 미치지 못하였다. 2) 저온처리시(低溫處理時) media내 morphine과 naloxone은 $(^3H)-morphine$ 의 maximal saturable binding 과 $K_D$치(値)를 증가(增加) 시켰다. 3) 저온처리시(低溫處理時) media내(內) $K^+$감소(減少), $Mg^{++}$제거 또는$Mn^{++}$첨가(添加)는 $(^3H)-morphine$의 saturable binding을 현저(顯著)히 증가(增加)시켰고, $Na^+$감소(減少), $Ca^{++}$증가(增加)는 saturable binding에 영향(影響)을 미치지 못하였다. 4) 저온처리시(低溫處理時) media내(內) morphine에 의한 $(^3H)-morphine$의 saturable binding증가(增加)는 media내(內) $Na^+$감소(減少), $K^+$감소(減少), $Mg^{++}$제거 또는 $Mn^{++}$첨가(添加)로는 영향(影響) 받지 않았으나 $Ca^{++}$증가(增加)로 억제(抑制)되었고, media내(內) naloxone에 의한 saturable binding증가(增加)는 $Mn^{++}$첨가(添加)는 영향(影響)받지 않았으나 media내(內) $Na^+$감소(減少), $K^+$감소(減少), $Ca^{++}$증가(增加) 또는 $Mg^{++}$제거로 억제(抑制)되었다. 이상(以上) 실험성적(實驗成績)은 저온처리(低溫處理) 및 저온처리시(低溫處理時) media내(內) morphine 또는 naloxone이 opiate수용체(受容體)의 양적(量的)인 변동(變動)과 또는 친화력(親和力)의 변동(變動)을 유발(誘發)하며, media내(內) 전해질조성(電解質組成)이 이들 변동(變動)에 영향(影響)을 미침을 시사(示唆)한다.

• Asian-Australasian Journal of Animal Sciences
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• 제24권2호
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• pp.239-245
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• 2011

This study was conducted to determine the effects of excess vitamin A on alkaline phosphatase (ALP) activity, contents of calcium-binding protein (CaBP), bone gla-protein (BGP) in culture medium and CaBP mRNA expression in chicken osteoblasts in vitro. Osteoblastic cells in the tibia from 1-day-old Arbor Acre broiler chickens were isolated using enzyme digestion. The subconfluenced cells were divided into eight treatments with six replicates in each treatment and cultured in a medium containing either vehicle or different levels of vitamin A (0, 0.2, 0.6, 1.0, 2.0, 5.0, 10.0 and $20.0\;{\mu}g$/ml), and the control received an equivalent volume of ethanol. The incubation lasted 48 h. The results showed that vitamin A down-regulated ALP activity in the culture medium as well as CaBP mRNA expression of osteoblasts in a linear dose-dependent manner (p = 0.124 and p<0.10, respectively), and suppressed the contents of BGP and CaBP in the culture medium in a quadratic dose-dependent manner (p<0.05 and p<0.10, respectively) with increasing addition of vitamin A. The addition of 0-$0.2\;{\mu}g$/ml vitamin A to the culture medium increased ALP activity, BGP and CaBP contents as well as CaBP mRNA expression compared with other groups, but positive effects of vitamin A tended to be suppressed when vitamin A was increased to $1.0\;{\mu}g$/ml, and adverse effects occurred when vitamin A was increased to 10.0-$20.0\;{\mu}g$/ml. These results implied that there was a threshold level of vitamin A inclusion beyond which inhibitory effects occurred, and the mechanism by which overdose of vitamin A reduced bone growth in chickens was probably reduced osteoblastic cell activity, and inhibited expression of CaBP mRNA and CaBP secretion.

• BMB Reports
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• 제43권3호
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• pp.158-163
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• 2010

Calumenin is a multiple EF-hand $Ca^{2+}$-binding protein located in the endo/sarcoplasmic reticulum of mammalian hearts. Calumenin belongs to the CREC family of $Ca^{2+}$-binding proteins having multiple EF-hands. $Ca^{2+}$ homeostasis in the sarcoplasmic reticulum (SR) of mammalian hearts is maintained by RyR2, SERCA2 and other associated SR resident proteins. Evidence suggests that calumenin interacts with RyR2 and SERCA2, and therefore changes in the expression of calumenin could alter $Ca^{2+}$ cycling in mouse heart. In this review, current knowledge of the biochemical and functional roles of calumenin in mouse heart is described.

• The Korean Journal of Physiology and Pharmacology
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• 제5권5호
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• pp.397-405
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• 2001

The ryanodine receptor, a $Ca^{2+}$ release channel of the sarcoplasmic reticulum (SR), is responsible for the rapid release of $Ca^{2+}$ that activates cardiac muscle contraction. In the excitation-contraction coupling cascade, activation of SR $Ca^{2+}$ release channel is initiated by the activity of sarcolemmal $Ca^{2+}$ channels, the dihydropyridine receptors. Previous study showed that the relaxation defect of diabetic heart was due to the changes of the expressional levels of SR $Ca^{2+}$ATPase and phospholamban. In the diabetic heart contractile abnormalities were also observed, and one of the mechanisms for these changes could include alterations in the expression and/or activity levels of various $Ca^{2+}$ regulatory proteins involving cardiac contraction. In the present study, underlying mechanisms for the functional derangement of the diabetic cardiomyopathy were investigated with respect to ryanodine receptor, and dihydropyridine receptor at the transcriptional and translational levels. Quantitative changes of ryanodine receptors and the dihydropyridine receptors, and the functional consequences of those changes in diabetic heart were investigated. The levels of protein and mRNA of the ryanodine receptor in diabetic rats were comparable to these of the control. However, the binding capacity of ryanodine was significantly decreased in diabetic rat hearts. Furthermore, the reduction in the binding capacity of ryanodine receptor was completely restored by insulin. This result suggests that there were no transcriptional and translational changes but functional changes, such as conformational changes of the $Ca^{2+}$ release channel, which might be regulated by insulin. The protein level of the dihydropyridine receptor and the binding capacity of nitrendipine in the sarcolemmal membranes of diabetic rats were not different as compared to these of the control. In conclusion, in diabetic hearts, $Ca^{2+}$ release processes are impaired, which are likely to lead to functional derangement of contraction of heart. This dysregulation of intracellular $Ca^{2+}$ concentration could explain for clinical findings of diabetic cardiomyopathy and provide the scientific basis for more effective treatments of diabetic patients. In view of these results, insulin may be involved in the control of intracellular $Ca^{2+}$ in the cardiomyocyte via unknown mechanism, which needs further study.

• The Korean Journal of Physiology and Pharmacology
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• 제1권5호
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• pp.485-493
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• 1997

We investigated the effect of ${\alpha}-adrenergic$ and cholinergic receptor agonists on $Ca^{2+}$ current in adult rat trigeminal ganglion neurons using whole-cell patch clamp methods. The application of acetylcholine, carbachol, and oxotremorine ($50\;{\mu}M\;each$) produced a rapid and reversible reduction of the $Ca^{2+}$ current by $17{\pm}6%,\;19{\pm}3%,\;and\;18{\pm}4%$, respectively. Atropine, a muscarinic antagonist, blocked carbachol- induced $Ca^{2+}$ current inhibition to $3{\pm}1%$. Norepinephrine ($50\;{\mu}M$) reduced $Ca^{2+}$ current by $18{\pm}2%$, while clonidine ($50\;{\mu}M$), an ${\alpha}2-adrenergic$ receptor agonist, inhibited $Ca^{2+}$ current by only $4{\pm}1%$. Yohimbine, an ${\alpha}2-adrenergic$ receptor antagonist, did not block the inhibitory effect of norepinephrine on $Ca^{2+}$ current, whereas prazosin, an ${\alpha}1-adrenergic$ receptor antagonist, attenuated the inhibitory effect of norepinephrine on $Ca^{2+}$ current to $6{\pm}1%$. This pharmacology contrasts with ${\alpha}2-adrenergic$ receptor modulation of $Ca^{2+}$ channels in rat sympathetic neurons, which is sensitive to clonidine and blocked by yohimbine. Our data suggest that the modulation of voltage dependent $Ca^{2+}$ channel by norepinephrine is mediated via an α1-adrenergic receptor. Pretreatment with pertussis toxin (250 ng/ml) for 16 h greatly reduced norepinephrine- and carbachol-induced $Ca^{2+}$ current inhibition from $17{\pm}3%\;and\;18{\pm}3%\;to\;2{\pm}1%\;and\;2{\pm}1%$, respectively. These results demonstrate that norepinephrine, through an ${\alpha}1-adrenergic$ receptor, and carbachol, through a muscarinic receptor, inhibit $Ca^{2+}$ currents in adult rat trigeminal ganglion neurons via pertussis toxin sensitive GTP-binding proteins.