Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USA.
Structure. 2011 Oct 12;19(10):1424-32. doi: 10.1016/j.str.2011.08.001. Epub 2011 Sep 1.
Mechanism of G protein-coupled receptor (GPCR) activation and their modulation by functionally distinct ligands remains elusive. Using the technique of amide hydrogen/deuterium exchange coupled with mass spectrometry, we examined the ligand-induced changes in conformational states and stability within the beta-2-adrenergic receptor (β(2)AR). Differential HDX reveals ligand-specific alterations in the energy landscape of the receptor's conformational ensemble. The inverse agonists timolol and carazolol were found to be most stabilizing even compared with the antagonist alprenolol, notably in intracellular regions where G proteins are proposed to bind, while the agonist isoproterenol induced the largest degree of conformational mobility. The partial agonist clenbuterol displayed conformational effects found in both the inverse agonists and the agonist. This study highlights the regional plasticity of the receptor and characterizes unique conformations spanning the entire receptor sequence stabilized by functionally selective ligands, all of which differ from the profile for the apo receptor.
G 蛋白偶联受体（GPCR）的激活机制及其与功能不同配体的相互作用仍然难以捉摸。本研究采用酰胺氢/氘交换结合质谱技术，检测了β2-肾上腺素能受体（β2AR）构象状态和稳定性的配体诱导变化。差异 HDX 揭示了受体构象整体的配体特异性能量景观变化。反向激动剂替莫洛尔和卡唑洛尔被发现比拮抗剂心得安更稳定，特别是在 G 蛋白结合的细胞内区域，而激动剂异丙肾上腺素诱导了最大程度的构象灵活性。部分激动剂克仑特罗显示出与反向激动剂和激动剂相似的构象效应。本研究强调了受体的区域可塑性，并描述了由功能选择性配体稳定的跨越整个受体序列的独特构象，这些构象都与apo 受体的特征不同。
