The functional significance of the last 5 residues of the C-terminus of cardiac troponin I.
The functional significance of the last 5 residues of the C-terminus of cardiac troponin I.
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DOI：
10.1016/j.abb.2016.02.023
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发表时间：
2016-07-01
影响因子：
3.9
通讯作者：
Gomes AV
中科院分区：
文献类型：
--
作者：
Gilda JE;Xu Q;Martinez ME;Nguyen ST;Chase PB;Gomes AV
心肌肌钙蛋白I(CTnI)的C末端区域(CTnI)在心脏功能中起重要作用，因为去除人cTnI的最后17个C末端残基与心肌顿抑有关。为了研究cTnI的C末端区域，在人cTnI中产生了三个C末端缺失突变：Δ1(缺失210个残基)、Δ3(缺失208~210个残基)和Δ5(缺失206~210个残基)。哺乳动物双杂交研究表明，与野生型cTnI相比，Δ3和Δ5突变体与心肌肌钙蛋白C(CTnC)或心肌肌钙蛋白T(CTnT)之间的相互作用受到损害。含有2-[4‘-(碘乙酰氨基)苯胺基]萘-6-磺酸(IAANS)标记的cTNC的肌钙蛋白复合体显示，含有cTnIΔ5的肌钙蛋白复合体的钙亲和力略有增加(P<；0.05)，而cTnIΔ1-和Δ3的肌钙蛋白复合体的钙亲和力与野生型肌钙蛋白没有差异。体外运动分析表明，与野生型cTnI相比，所有截短突变体都能增加细胞内钙离子依赖的运动能力。这些结果表明，cTnI的最后5个C端残基影响cTnI与cTnC和cTnT的结合，影响细丝滑动对钙的依赖性，并证明了cTnI这一区域的重要性。
The C-terminal region of cardiac troponin I (cTnI) is known to be important in cardiac function, as removal of the last 17 C-terminal residues of human cTnI has been associated with myocardial stunning. To investigate the C-terminal region of cTnI, three C-terminal deletion mutations in human cTnI were generated: Δ1 (deletion of residue 210), Δ3 (deletion of residues 208-210), and Δ5 (deletion of residues 206-210). Mammalian two-hybrid studies showed that the interactions between cTnI mutants and cardiac troponin C (cTnC) or cardiac troponin T (cTnT) were impaired in Δ3 and Δ5 mutants when compared to wild-type cTnI. Troponin complexes containing 2-[4’-(iodoacetamido) anilino] naphthalene-6-sulfonic acid (IAANS) labeled cTnC showed that the troponin complex containing cTnI Δ5 had a small increase in Ca2+ affinity (P < 0.05); while the cTnI Δ1- and Δ3 troponin complexes showed no difference in Ca2+ affinity when compared to wild-type troponin. In vitro motility assays showed that all truncation mutants had increased Ca2+ dependent motility relative to wild-type cTnI. These results suggest that the last 5 C-terminal residues of cTnI influence the binding of cTnI with cTnC and cTnT, affects the Ca2+-dependence of filament sliding, and demonstrate the importance of this region of cTnI.