TM2-TM7 interaction in coupling movement of transmembrane helices to activation of the angiotensin II type-1 receptor
TM2-TM7 interaction in coupling movement of transmembrane helices to activation of the angiotensin II type-1 receptor
复制标题
DOI：
10.1074/jbc.m211338200
复制
发表时间：
2003-02-07
影响因子：
4.8
通讯作者：
Karnik, SS
中科院分区：
文献类型：
--
作者：
Miura, S;Zhang, JL;Karnik, SS
激动剂诱导的跨膜（TM）螺旋的刚体运动已被确立为G蛋白偶联受体激活的统一机制。在尝试测量血管紧张素II（AT（1））的1型受体活化期间的特异性构象转变时，我们发现第二TM螺旋中Cys（76）的可接近性降低，表明TM 2的取向改变（Miura，S.，和Karnik，S. S.（2002）J.Biol.Chem.277，24299-24305）。现在，我们提供的证据表明，TM 2螺旋运动在调节AT_1受体的激活状态中起作用，并且这种作用可能涉及TM 2和TM 7之间的相互作用。TM 7中天然Cys 296的丙氨酸取代导致Cys 2ss的可接近性增加和对结合激动剂的反应减弱。当与F77 A和N111 G突变体组合时，C296 A突变的两种作用都被抑制。TM 7构象和C296 A突变改变的Cys（289）的敏感性被TM 2中的F77 A突变抑制以挽救功能。我们发现，F77 A突变体改变TM 2和TM 7的方向，但不诱导抑制C296 A突变体的影响的组成型活性。因此，TM 2和TM 7的相互作用对于AT（1）受体的跨膜信号转导是重要的。
Agonist-induced rigid body motion of transmembrane (TM) helices has been established as a unifying mechanism in the activation of the G protein-coupled receptors. In attempts to measure specific conformational transitions during the activation of the type 1 receptor for angiotensin II (AT(1)), we found a decrease in accessibility of Cys(76) in the second TM helix, suggesting that the orientation of TM2 is altered (Miura, S., and Karnik, S. S. (2002) J. Biol. Chem. 277, 24299-24305). Now we provide evidence that the TM2 helical movement plays a role in regulating the activated state of the AT, receptor, and this role may involve an interaction between TM2 and TM7. Alanine substitution of native Cys296 in TM7 leads to increased accessibility of Cys2ss and diminished response to bound agonist. Both effects of the C296A mutation are suppressed when combined with F77A and N111G mutants. The TM7 conformation and the sensitivity of Cys(289) altered by C296A mutation are suppressed by the F77A mutation in TM2 to salvage function. We show that the F77A mutant alters orientation of both TM2 and TM7 but does not induce constitutive activity in suppressing the C296A mutant effects. Thus, interaction of TM2 and TM7 is important for transmembrane signal transduction in the AT(1) receptor.