Ichida Seiji, Abe Junichi, Yu-an Zhang, Minami Takeshi, Wada Tetsuyuki, Yazawa Michio, Sohma Hitoshi
Department of Biological Chemistry, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan.
Neurochem Res. 2003 Dec;28(12):1813-8. doi: 10.1023/a:1026163523145.
To clear the structural specificity of calmodulin (CaM) on the specific 125I-omega-CTX binding to crude membranes from whole chick brain, the following experiments were investigated in this study: (i) the attenuating effect of semisynthetic tetrahydroisoquinoline derivatives on the inhibitory effect of Ca2+/CaM, (ii) the effects of chimeras of yeast and chicken Ca2+/CaM, and (iii) the effects of Ca2+-binding proteins (such as troponin c, S 100 a and b, and annexin I, III-V). The inhibitory effect of Ca2+/CaM was attenuated by isoquinoline derivatives (PX 28, 34, 216, 224, and CPU57) and a CaM antagonist W-7. PX 34, a typical synthesized isoquinoline derivative, showed the attenuating effect in a dose-dependent manner. The ED50 value for the attenuating effect of PX 34 was about 20 microM, which is similar to that of W-7 reported previously. Some chimeric CaMs such as YC 51-53 (which are close to the properties of vertebrate CaM) showed a significant inhibitory effect on the specific 125I-omega-CTX binding, but YC 129 and 130 (which retain the properties of yeast CaM), troponin c, S100 a, b, and annexin I, III-V had no effect on the specific 125I-omega-CTX binding. These results suggest that the characteristic structure containing the EF-hand structure of CaM itself is needed to cause the inhibitory effect on the specific 125I-omega-CTX binding.
为了明确钙调蛋白（CaM）对全鸡脑粗膜上特异性¹²⁵I - ω - CTX结合的结构特异性，本研究进行了以下实验：（i）半合成四氢异喹啉衍生物对Ca²⁺/CaM抑制作用的减弱效应；（ii）酵母和鸡Ca²⁺/CaM嵌合体的效应；（iii）Ca²⁺结合蛋白（如肌钙蛋白c、S100 a和b以及膜联蛋白I、III - V）的效应。异喹啉衍生物（PX 28、34、216、224和CPU57）以及CaM拮抗剂W - 7减弱了Ca²⁺/CaM的抑制作用。典型的合成异喹啉衍生物PX 34呈剂量依赖性地显示出减弱效应。PX 34减弱效应的半数有效浓度（ED50）值约为20微摩尔，这与先前报道的W - 7的值相似。一些嵌合CaM，如YC 51 - 53（其性质接近脊椎动物CaM）对特异性¹²⁵I - ω - CTX结合表现出显著抑制作用，但YC 129和130（保留酵母CaM的性质）、肌钙蛋白c、S100 a、b以及膜联蛋白I、III - V对特异性¹²⁵I - ω - CTX结合没有影响。这些结果表明，CaM自身包含EF - 手结构的特征结构是对特异性¹²⁵I - ω - CTX结合产生抑制作用所必需的。
