The intrinsic conformational plasticity of membrane proteins directly influences the magnitude of the orientational-dependent NMR interactions such as dipolar couplings (DC) and chemical shift anisotropy (CSA). As a result, the conventional cross-polarization (CP)-based techniques mainly capture the more rigid regions of membrane proteins, while the most dynamic regions are essentially invisible. Nonetheless, dynamic regions can be detected using experiments in which polarization transfer takes place via J-coupling interactions. Here, we review our recent efforts to develop single and dual acquisition pulse sequences with either 1H or 13C detection that utilize both DC and J-coupling mediated transfer to detect both rigid and mobile regions of membrane proteins in native-like lipid environments. We show the application of these new methods for studying the conformational equilibrium of a single-pass membrane protein, phospholamban, which regulates the calcium transport across the sarcoplasmic reticulum (SR) membrane by interacting with the SR Ca2+-ATPase. We anticipate that these methods will be ideal to portray the complex dynamics of membrane proteins in their native environments.

中文翻译：

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使用偶极耦合和 J 耦合介导的 MAS 固态 NMR 实验探测膜蛋白的基态和构象激发态

膜蛋白的内在构象可塑性直接影响方向依赖性 NMR 相互作用的大小，例如偶极耦合 (DC) 和化学位移各向异性 (CSA)。因此，传统的基于交叉极化（CP）的技术主要捕获膜蛋白的刚性区域，而最动态的区域基本上是不可见的。尽管如此，可以使用通过 J 耦合相互作用发生偏振转移的实验来检测动态区域。在这里，我们回顾了我们最近开发具有 1H 或 13C 检测的单采集脉冲序列和双采集脉冲序列的努力，该序列利用 DC 和 J 耦合介导的转移来检测类天然脂质环境中膜蛋白的刚性和移动区域。我们展示了这些新方法在研究单通道膜蛋白（受磷蛋白）构象平衡中的应用，该蛋白通过与 SR Ca2+-ATP 酶相互作用来调节跨肌浆网 (SR) 膜的钙转运。我们预计这些方法将非常适合描绘膜蛋白在其天然环境中的复杂动态。