圣犹达儿童研究医院Georgios Skiniotis小组宣布他们研究出μ-阿片受体配体效能的非平衡态快照。这一研究成果于2025年12月22日发表在国际顶尖学术期刊《自然》上。

假设这种信号传导效果的差异可能在非平衡条件下的中间状态下被结构捕获，该课题组采用了时间分辨（TR）冷冻电镜方法来观察GTP诱导的Gαiβγ异源三聚体被μ-阿片受体（MOR）结合到三种配体上，表现出部分、完全或超激动作用。研究团队解决了沿着G蛋白激活途径的构象状态集合，包括以前未观察到的中间状态，使他们能够可视化受体动力学作为结合配体的功能。结果表明，配体在状态占用和构象稳定性方面存在依赖差异，配体效能的提高与受体跨膜（TM）螺旋5和6的动力学增加有关。

此外，小组确定了GTP诱导的Gi与Gs激活的关键机制差异，这可能是它们不同激活动力学的基础。通过分子动力学（MD）模拟和单分子荧光分析，这些发现提供了GPCR-G-蛋白相互作用的动态结构景观，并表明部分激动剂可能在G-蛋白激活过程中产生“动力学陷阱”。

据介绍，相同G蛋白偶联受体（GPCR）的不同配体在不同程度上激活细胞内信号伙伴，但驱动这些差异的分子机制仍然是未知的。

附：英文原文

Title: Non-equilibrium snapshots of ligand efficacy at the μ-opioid receptor

Author: Robertson, Michael J., Modak, Arnab, Papasergi-Scott, Makaa M., Hu, Miaohui, Peroto, Maria Claudia, Varga, Balazs R., Majumdar, Susruta, Kalathur, Ravi, Blanchard, Scott C., Skiniotis, Georgios

Issue&Volume: 2025-12-22

Abstract: Distinct ligands for the same G-protein coupled receptor (GPCR) activate intracellular signaling partners to varying extents, but the molecular mechanisms driving these differences remain elusive. Hypothesizing that such differences in signaling efficacy may be captured structurally in intermediate states under non-equilibrium conditions, we implemented a time-resolved (TR) cryo-EM approach to visualize the GTP-induced activation of the Gαiβγ heterotrimer by the μ-opioid receptor (MOR) bound to three ligands displaying partial, full, or super-agonism on the receptor1. We resolved ensembles of conformational states along the G-protein activation pathway, including a previously unobserved intermediate state that enabled us to visualize receptor dynamics as a function of bound ligand. The results demonstrate ligand-dependent differences in state occupancy and conformational stability, with higher ligand efficacy correlating with increased dynamics of the receptor’s transmembrane (TM) helices 5 and 6. Furthermore, we identify key mechanistic differences in the GTP-induced activation of Gi compared to Gs that likely underlie their distinct activation kinetics. Corroborated by molecular dynamics (MD) simulations and single-molecule fluorescence assays, these findings provide a dynamic structural landscape of GPCR-G-protein interactions for ligands of different efficacy and suggest partial agonists may produce a ‘kinetic trap’ during G-protein activation.

DOI: 10.1038/s41586-025-10056-4

Source: https://www.nature.com/articles/s41586-025-10056-4