Sundaralingam M, Bergstrom R, Strasburg G, Rao S T, Roychowdhury P, Greaser M, Wang B C
Science. 1985 Feb 22;227(4689):945-8. doi: 10.1126/science.3969570.
The x-ray structure of chicken skeletal muscle troponin C (TnC), the Ca2+-binding subunit of the troponin complex, shows that the protein is about 70 angstroms long with an unusual dumbbell shape. The carboxyl and amino domains are separated by a single long alpha helix of about nine turns. Only the two high-affinity Ca2+-Mg2+ sites of the COOH-domain are occupied by metal ions resulting in conformational differences between the COOH- and NH2-domains. These differences are probably important in the triggering of muscle contraction by TnC. Also the structure of TnC is relevant in understanding the function of other calcium-regulated proteins, in particular that of calmodulin because of its strong similarity in amino acid sequence.
鸡骨骼肌肌钙蛋白C（TnC）是肌钙蛋白复合体的钙离子结合亚基，其X射线结构表明该蛋白质长约70埃，呈不寻常的哑铃状。羧基结构域和氨基结构域由一个约九圈的单一长α螺旋隔开。只有COOH结构域的两个高亲和力Ca2+-Mg2+位点被金属离子占据，导致COOH结构域和NH2结构域之间存在构象差异。这些差异可能在TnC触发肌肉收缩中起重要作用。此外，TnC的结构对于理解其他钙调节蛋白的功能也很重要，特别是钙调蛋白，因为它们在氨基酸序列上有很强的相似性。
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