Functional importance of Ca2+-deficient N-terminal lobe of molluscan troponin C in troponin regulation.
Functional importance of Ca2+-deficient N-terminal lobe of molluscan troponin C in troponin regulation.
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软体动物肌钙蛋白 C 的 Ca2 缺陷 N 端叶在肌钙蛋白调节中的功能重要性。
DOI：
10.1016/j.abb.2005.01.004
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发表时间：
2005
影响因子：
3.9
通讯作者：
T. Ojima
中科院分区：
文献类型：
--
作者：
Teppei Doi;Ai Satoh;Hiroyuki Tanaka;A. Inoue;F. Yumoto;M. Tanokura;I. Ohtsuki;K. Nishita;T. Ojima
软体动物肌钙蛋白C(TNC)N-末端的钙结合位点I和II由于与钙离子连接的氨基酸残基的取代而失去了与钙结合的能力。为了评估钙缺乏的N-末端叶在软体动物肌钙蛋白钙调节功能中的功能重要性，我们分别构建了由兔快肌和鱿鱼套膜肌TnCs的N-末端叶和赤潮扇贝TnC、TnCRA和TnCSA的C-末端叶组成的嵌合TnCs。并与赤潮扇贝野生型TnCAA(TnCAA)的生化特性进行了比较。根据45Ca~(2+)的平衡透析法，TnCRA和TnCSA分别以化学计量比结合3molCa~(2+)/mol和1molCa~(2+)/mol，与它们的一级结构相一致。所有嵌合的TNCs在钙离子结合后在280-290 nm处表现出不同的紫外吸收光谱，并与赤潮扇贝肌钙蛋白I形成稳定的络合物，即使在6M尿素存在的情况下也是如此。然而，当肌钙蛋白复合体由嵌合的TNCs和AKZARA扇贝肌钙蛋白T和肌钙蛋白I构建时，它们表现出不同的钙调节能力，这取决于TNC物种。因此，含有TnCSA的肌钙蛋白与含有TnCAA的肌钙蛋白一样，对兔肌动球蛋白-赤潮扇贝原肌球蛋白的MG-ATPase活性具有很高的钙敏感性，而含有TnCRA的肌钙蛋白几乎不具有钙敏感性。我们的发现表明，软体动物TNC的N-末端叶在调节软体动物肌钙蛋白方面发挥着重要作用，尽管它不能结合钙离子。
Ca2+-binding sites I and II in the N-terminal lobe of molluscan troponin C (TnC) have lost the ability to bind Ca2+due to substitutions of the amino acid residues responsible for Ca2+liganding. To evaluate the functional importance of the Ca2+-deficient N-terminal lobe in the Ca2+-regulatory function of molluscan troponin, we constructed chimeric TnCs comprising the N-terminal lobes from rabbit fast muscle and squid mantle muscle TnCs and the C-terminal lobe from akazara scallop TnC, TnCRA, and TnCSA, respectively. We characterized their biochemical properties as compared with those of akazara scallop wild-type TnC (TnCAA). According to equilibrium dialysis using45Ca2+, TnCRA, and TnCSAbound stoichiometrically 3mol Ca2+/mol and 1mol Ca2+/mol, respectively, as expected from their primary structures. All the chimeric TnCs exhibited difference-UV-absorption spectra at around 280–290nm upon Ca2+binding and formed stable complexes with akazara scallop troponin I, even in the presence of 6M urea, if Ca2+was present. However, when the troponin complexes were constructed from chimeric TnCs and akazara scallop troponin T and troponin I, they showed different Ca2+-regulation abilities from each other depending on the TnC species. Thus, the troponin containing TnCSAconferred as high a Ca2+sensitivity to Mg-ATPase activity of rabbit actomyosin–akazara scallop tropomyosin as did the troponin containing TnCAA, whereas the troponin containing TnCRAconferred virtually no Ca2+sensitivity. Our findings indicate that the N-terminal lobe of molluscan TnC plays important roles in molluscan troponin regulation, despite its inability to bind Ca2+.
兔快速骨骼肌肌钙蛋白 C 的 cDNA 克隆的分离和序列。与钙调蛋白和小清蛋白的同源性。
DOI：
--
发表时间：
1987
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Zot,AS;Potter,JD;Strauss,WL
通讯作者：
Strauss,WL
龙虾肌钙蛋白 C：三种亚型的氨基酸序列。
影响因子：
3.9
作者：
Garone,L;Theibert,JL;Miegel,A;Maeda,Y;Murphy,C;Collins,JH
通讯作者：
Collins,JH
鸡骨骼肌肌钙蛋白 C 在二钙状态下的精细结构，分辨率为 2-A。
DOI：
--
发表时间：
1988
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Satyshur,KA;Rao,ST;Pyzalska,D;Drendel,W;Greaser,M;Sundaralingam,M
通讯作者：
Sundaralingam,M