GABAB受体（GABABR）是中枢神经系统中主要的抑制型神经递质GABA的代谢型受体，也属于G蛋白偶联受体家族C组成员之一。它参与调节了多种神经系统生理功能，是重要的药物靶点。偏向性配体的概念细化了受体的激活效应，并期望有更灵敏的检测手段衡量受体激活的细微变化。直接对受体激活起始阶段，即受体激活G蛋白三聚体机制的研究避免了下游信号通路研究的复杂性。因而，在本项目中，我们期望利用BRET技术研究GABABR对Ga蛋白尤其是其不同亚型的激活机制，包括鉴定GABABR不同亚基与Ga，Gbg相互作用的重要结构域，测试受体激活过程中，不同的Ga亚型与Gbg相互作用变化的差异，最后检测不同Ga亚型对GABABR介导的下游信号通路的影响。本研究将阐明GABABR激活信号从受体到G蛋白的传导过程，为建立基于不同G蛋白亚型的偏向性配体筛选模型提供理论基础，并为揭示不同偏向性配体的潜在功能提供实验依据。

GABAB receptor is the metabotropic receptor of gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the central nervous system (CNS) and also is a member of G protein coupled receptor family (GPCR) group C. It is involved in multipal functions in CNS and is a very important drug target. The concept of ligand biased signaling has classified receptor function and asked for highly sensitive pharmacological assays to fully capture the nuances of ligand activity. Directly exploring the initial step of GABABR activation of heterotrimeric G proteins avoid the complexity of downstream signaling pathway and regulation events. So in this project, we propose to use BRET technique to study the mechanism of GABABR-activated G protein, especially different Galpha protein subfamily. The project includes: identify the key domain of GB1 and GB2 subunit interact with Galpha, Gbeta/gamma, detect the dynamic interaction change between Galpha and Gbeta/gamma following GABABR activation, finally investigate the roles of different Galpha subfamily in GABABR-mediated downstream pathway. This research will clarify the dynamic signal transfer directly from receptor to G protein and provide evidence for biased ligand screening based on different G protein subfamily and also the potential role in GABABR function modulation.