Mechanism of activation and modulation in human GABA(B) receptor

项目总结 抑制性神经递质GABA通过以下途径在大脑中产生缓慢而持久的抑制 代谢性GABAB受体的激活(GABABR)。GABR信号中的缺陷已经被 与各种神经和情绪障碍有关，包括痉挛、癫痫、成瘾和 焦虑。GABABR是C类G蛋白偶联受体(GPCR)家族的成员，该家族通常 具有二聚体的功能，并具有较大的胞外结构域。根本问题依然存在 关于这些C类受体激活和调节的分子机制。 GABR是GABAB1和GABAB2亚基的异源二聚体，受钾的调节 通道四聚含结构域(KCTD)蛋白辅助亚基。在这项提案中，我们将 发展全长GABABR、其辅助亚基及其与G-的络合物的结构模型 蛋白。以我们的细胞外和细胞内成分的结构模型为基础 人类GABR，我们建议确定GABR辅助亚基的结构多样性 KCTDS，并阐明了KCTDS与G蛋白之间的相互作用(目标1)，描述了分子 GABR和KCTD之间的关联，并确定其对GABABR信号的影响(目标2)，以及 求解全长GABABR在多种官能态下的结构，表征变构 GABABR和G蛋白之间的相互作用(目标3)。我们将使用创新的战略 结合结构和功能分析，包括低温电子显微镜(EM)和纳米盘。 综上所述，这些研究将促进我们对GABA在体内作用的分子基础的理解。 大脑，导致治疗神经疾病的新疗法的发展。

PROJECT SUMMARY The inhibitory neurotransmitter GABA produces slow and prolonged inhibition in the brain through activation of metabotropic GABAB receptors (GABABR). Defects in GABABR signaling have been implicated in various neurological and mood disorders including spasticity, epilepsy, addiction and anxiety. GABABR is a member of the class C G protein-coupled receptor (GPCR) family, which typically functions as a dimer and possesses large extracellular domains. Fundamental questions remain concerning the molecular mechanisms underlying activation and modulation of these class C receptors. The GABABR is a heterodimer of GABAB1 and GABAB2 subunits and is modulated by the potassium channel tetramerization domain-containing (KCTD) protein auxiliary subunits. In this proposal, we will develop structural models for full-length GABABR, its auxiliary subunits and their complexes with G- protein. Building on our structural models for both the extracellular and intracellular components of human GABABR, we propose to determine the structural diversity of GABABR auxiliary subunits KCTDs, and elucidate the interactions between KCTDs and G proteins (Aim 1), describe the molecular association between GABABR and KCTD, and determine its impact on GABABR signaling (Aim 2), and solve the structures of full-length GABABR in multiple functional states, characterizing the allosteric interaction between the GABABR and G proteins (Aim 3). We will use an innovative strategy of combining structural and functional analyses, including cryo-electron microscopy (EM) and nanodiscs. Together, these studies will advance our understanding of the molecular basis of GABA action in the brain, leading to the development of novel therapeutics for treating neurological diseases.