Glycine receptors (GlyR) conduct inhibitory glycinergic neurotransmission in the spinal cord and the brainstem. They play an important role in muscle tone, motor coordination, respiration, and pain perception. However, the mechanism underlying GlyR activation remains unclear. There are five potential glycine binding sites in α1 GlyR, and different binding patterns may cause distinct activation or desensitization behaviors. In this study, we investigated the coupling of protein conformational changes and glycine binding events to elucidate the influence of binding patterns on the activation and desensitization processes of α1 GlyRs. Subsequently, we explored the energetic distinctions between the apical and lateral pathways during α1 GlyR conduction to identify the pivotal factors in the ion conduction pathway preference. Moreover, we predicted the mutational effects of the key residues and verified our predictions using electrophysiological experiments. For the mutants that can be activated by glycine, the predictions of the mutational directions were all correct. The strength of the mutational effects was assessed using Pearson’s correlation coefficient, yielding a value of −0.77 between the calculated highest energy barriers and experimental maximum current amplitudes. These findings contribute to our understanding of GlyR activation, identify the key residues of GlyRs, and provide guidance for mechanistic studies on other pLGICs.

中文翻译：

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探索甘氨酸受体的激活过程


甘氨酸受体（GlyR）在脊髓和脑干中传导抑制性甘氨酸神经传递。它们在肌张力、运动协调、呼吸和疼痛感知方面发挥着重要作用。然而，GlyR 激活的机制仍不清楚。 α1 GlyR 中有五个潜在的甘氨酸结合位点，不同的结合模式可能会导致不同的激活或脱敏行为。在这项研究中，我们研究了蛋白质构象变化和甘氨酸结合事件的耦合，以阐明结合模式对 α1 GlyR 激活和脱敏过程的影响。随后，我们探索了 α1 GlyR 传导过程中顶端和侧向通路之间的能量差异，以确定离子传导通路偏好的关键因素。此外，我们预测了关键残基的突变效应，并使用电生理学实验验证了我们的预测。对于可以被甘氨酸激活的突变体，突变方向的预测都是正确的。使用皮尔逊相关系数评估突变效应的强度，计算出的最高能垒与实验最大电流振幅之间的值为-0.77。这些发现有助于我们对 GlyR 激活的理解，识别 GlyR 的关键残基，并为其他 pLGIC 的机制研究提供指导。