Kataoka M, Mihara K, Tokunaga F
Department of Biology, Faculty of Science, Osaka University.
J Biochem. 1993 Oct;114(4):535-40. doi: 10.1093/oxfordjournals.jbchem.a124212.
The solution structure and calcium-dependent structural changes of recoverin, a 23 kDa calcium binding protein of vertebrate photoreceptors, have been studied by small-angle X-ray scattering and CD, as well as the effect of N-terminal myristoylation. The CD spectrum is not affected by N-terminal myristoylation, but strongly affected by Ca2+, indicating that N-terminal myristoylation alone does not cause a conformational change. The major conformational change in recoverin induced by Ca2+ is characterized as a decrease in the alpha-helical content of the protein and an increase in global size upon removal of Ca2+. In the presence of Ca2+, unmyristoylated recoverin is monomeric and globular in solution, while N-terminal myristoylation brings about aggregation. In the absence of Ca2+, unmyristoylated recoverin tends to aggregate, while myristoylated recoverin becomes monomeric and globular. These observations indicate that recoverin changes its surface properties depending on both calcium binding and N-terminal myristoylation. Melittin interacts non-specifically only with the myristoylated recoverin in the absence of Ca2+. This may be indicative of the properties of the interaction between recoverin and its normal physiological target enzyme.
已通过小角X射线散射和圆二色光谱（CD）研究了恢复蛋白（一种脊椎动物光感受器中23 kDa的钙结合蛋白）的溶液结构、钙依赖性结构变化以及N端肉豆蔻酰化的影响。CD光谱不受N端肉豆蔻酰化的影响，但受Ca2+的强烈影响，这表明单独的N端肉豆蔻酰化不会引起构象变化。Ca2+诱导的恢复蛋白的主要构象变化表现为蛋白质的α-螺旋含量降低，去除Ca2+后整体尺寸增加。在有Ca2+存在的情况下，未肉豆蔻酰化的恢复蛋白在溶液中呈单体球状，而N端肉豆蔻酰化会导致聚集。在没有Ca2+的情况下，未肉豆蔻酰化的恢复蛋白倾向于聚集，而肉豆蔻酰化的恢复蛋白则变为单体球状。这些观察结果表明，恢复蛋白根据钙结合和N端肉豆蔻酰化改变其表面性质。在没有Ca2+的情况下，蜂毒素仅与肉豆蔻酰化的恢复蛋白非特异性相互作用。这可能表明恢复蛋白与其正常生理靶酶之间相互作用的性质。
