Selective inhibition of α1A-adrenergic receptor signaling by RGS2 association with the receptor third intracellular loop
Selective inhibition of α1A-adrenergic receptor signaling by RGS2 association with the receptor third intracellular loop
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DOI：
10.1074/jbc.m502365200
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发表时间：
2005-07-22
影响因子：
4.8
通讯作者：
Hepler, JR
中科院分区：
文献类型：
--
作者：
Hague, C;Bernstein, LS;Hepler, JR
G蛋白信号调节因子（Regulators of G-protein signaling，RGS）直接作用于G α亚基，以增加GTP水解速率并终止信号传导。然而，参与确定其在细胞中的作用特异性的机制仍不清楚。最近的证据表明，RGS蛋白可能直接与G蛋白偶联受体相互作用，以调节其活性。通过使用生物化学、荧光成像和功能性方法，我们发现RGS 2在体外直接且选择性地结合于α（1A）-肾上腺素能受体（AR）的第三胞内环，并被未受刺激的α（1A）-AR募集到细胞质膜以抑制受体和G（q/11）信号传导。这种相互作用是特异性的，因为RGS 2不与高度同源的α（1B）-或α（1D）-AR相互作用，而密切相关的RGS 16不与任何α（1）-AR相互作用。RGS 2的N末端是与α（1A）-AR结合和抑制信号传导所必需的，并且发现α（1A）-AR i3环内的氨基酸Lys（219）、Ser（220）和Arg（238）对于这种相互作用是必需的。这些发现表明，某些RGS蛋白可以直接与优选的G蛋白偶联受体相互作用，以高度特异性调节其信号传导。
Regulators of G-protein signaling (RGS) proteins act directly on G alpha subunits to increase the rate of GTP hydrolysis and to terminate signaling. However, the mechanisms involved in determining their specificities of action in cells remain unclear. Recent evidence has raised the possibility that RGS proteins may interact directly with G-protein-coupled receptors to modulate their activity. By using biochemical, fluorescent imaging, and functional approaches, we found that RGS2 binds directly and selectively to the third intracellular loop of the alpha(1A)-adrenergic receptor (AR) in vitro, and is recruited by the unstimulated alpha(1A)-AR to the plasma membrane in cells to inhibit receptor and G(q/11) signaling. This interaction was specific, because RGS2 did not interact with the highly homologous alpha(1B)- or alpha(1D)-ARs, and the closely related RGS16 did not interact with any alpha(1)-ARs. The N terminus of RGS2 was required for association with alpha(1A)-ARs and inhibition of signaling, and amino acids Lys(219), Ser(220), and Arg(238) within the alpha(1A)-AR i3 loop were found to be essential for this interaction. These findings demonstrate that certain RGS proteins can directly interact with preferred G-protein-coupled receptors to modulate their signaling with a high degree of specificity.