Selective ligand-induced stabilization of active and desensitized parathyroid hormone type 1 receptor conformations
Selective ligand-induced stabilization of active and desensitized parathyroid hormone type 1 receptor conformations
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DOI：
10.1074/jbc.m202544200
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发表时间：
2002-10-11
影响因子：
4.8
通讯作者：
Ferrari, SL
中科院分区：
文献类型：
--
作者：
Bisello, A;Chorev, M;Ferrari, SL
对于许多G蛋白偶联受体，激动剂诱导的激活之后是脱敏、内化和再敏化。在大多数情况下，这些过程依赖于激动剂占据的受体与细胞质β-抑制蛋白的相互作用。配体诱导的分子内重排的受体负责脱敏与活性构象状态，这决定了两个配体的药理学性质和G蛋白偶联受体的生物活性，尚未完全阐明。在这里，我们确定甲状旁腺激素（PTH）相关蛋白和人甲状旁腺激素1型受体（PTH 1 Rc）和相关受体构象变化，导致β-抑制蛋白-2介导的脱敏之间的特定相互作用。在位置1处修饰的PTH相关蛋白类似物诱导受体的活性G蛋白偶联状态的选择性稳定，导致缺乏β-抑制蛋白-2向细胞膜的募集、持续的cAMP信号传导和缺乏配体-受体复合物内化。机械上，在位置1处修饰的配体，与PTH 1 Rc的螺旋VI的细胞外末端相互作用，产生不同于由同源激动剂诱导的跨膜螺旋V和VI的易位，导致第三胞内环的显著不同的构象。这些结果表明PTH 1 Rc及其配体之间的特异性相互作用如何稳定不同的构象状态，代表活性G蛋白偶联或脱敏β-抑制蛋白偶联受体状态。此外，他们确定PTH 1 Rc的持续生物活性可以通过适当设计的激动剂配体诱导。
For many G protein-coupled receptors, agonist-induced activation is followed by desensitization, internalization, and resensitization. In most cases, these processes are dependent upon interaction of agonist-occupied receptor with cytoplasmic beta-arrestins. The ligand-induced intramolecular rearrangements of the receptor responsible for the desensitized versus active conformational states, which dictate both the pharmacological properties of ligands and the biological activity of G protein-coupled receptors, have not been fully elucidated. Here, we identify specific interactions between parathyroid hormone (PTH)-related protein and the human PTH type 1 receptor (PTH1Rc) and the related receptor conformational changes that lead to beta-arrestin-2-mediated desensitization. PTH-related protein analogs modified at position 1 induced selective stabilization of the active G protein-coupled state of the receptor, resulting in lack of beta-arrestin-2 recruitment to the cell membrane, sustained cAMP signaling, and absence of ligand-receptor complex internalization. Mechanistically, the ligands modified at position 1, interacting with the extracellular end of helix VI of PTH1Rc, produced a translocation of transmembrane helices V and VI that differed from that induced by the cognate agonist, resulting in significantly different conformations of the third intracellular loop. These results show how specific interactions between PTH1Rc and its ligands may stabilize distinct conformational states, representing either the active G protein-coupled or a desensitized beta-arrestin-coupled receptor state. In addition, they establish that sustained biological activity of PTH1Rc may be induced by appropriately designed agonist ligands.