Dominant negative mutants of transducin-alpha that block activated receptor.
Dominant negative mutants of transducin-alpha that block activated receptor.
复制标题
阻断激活受体的转导蛋白-α 的显性负突变体。
DOI：
10.1021/bi060381e
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发表时间：
2006
期刊：
影响因子：
2.9
通讯作者：
Artemyev,NikolaiO
中科院分区：
文献类型：
--
作者：
Natochin,Michael;Barren,Brandy;Artemyev,NikolaiO
异源三聚体G蛋白α亚基中与显性负性RasSer17Asn对应的突变也可产生显性负效应。这些突变的机制仍然知之甚少。在这里，我们研究了转导素样嵌合GTα*的Ser43Cys和Ser43Asn突变体在视觉信号系统中的作用和机制。我们的分析表明，这两个突变体都降低了对GDP的亲和力，并可能以空的或部分占据的口袋状态存在。S43C和S43N保留了与GTβγ相互作用的能力，并作为异源三聚体蛋白与光激发视紫红质(R*)结合。与R*的相互作用是无效的，因为突变体未能与gtpγS结合并被激活。S43C和S43N可抑制R*依赖的GTα*和GTα的激活，这明显是通过阻断R*实现的。最后，两个GTα*突变体都缺乏与光传导效应蛋白PDE6的γ亚单位的相互作用。这些结果表明，GTα*的S43C和S43N突变体是显性的负性抑制物，其结合和阻断激活的受体的机制与RasSer17Asn相似。GTα截留R*的显性负性突变体，如S43C和S43N，可能成为探讨光传导信号异常所致视觉功能障碍机制的有用工具。
Mutations counterpart to dominant negative RasSer17Asn in the α-subunits of heterotrimeric G-proteins are known to also produce dominant negative effects. The mechanism of these mutations remains poorly understood. Here, we examined the effects and mechanism of the Ser43Cys and Ser43Asn mutants of transducin-like chimeric Gtα* in the visual signaling system. Our analysis showed that both mutants have reduced affinity for GDP and are likely to exist in an emptyor partially occupiedpocket state. S43C and S43N retained the ability to interact with Gtβγ and, as heterotrimeric proteins, bind to photoexcited rhodopsin (R*). The interaction with R* is unproductive as the mutants failed to bind GTPγS and become activated. S43C and S43N inhibited R*-dependent activation of Gtα* and Gtα, apparently by blocking R*. Finally, both Gtα* mutants lacked interaction with the γ-subunit of PDE6, an effector protein in phototransduction. These results indicate that the S43C and S43N mutants of Gtα* are dominant negative inhibitors that bind and block the activated receptor in a mechanism that parallels that of RasSer17Asn. Dominant negative mutants of Gtα sequestering R*, such as S43C and S43N, may become useful instruments in probing the mechanisms of visual dysfunctions caused by abnormal phototransduction signaling.