腺环酶激活剂Gsalpha 的晶体结构
R K Sunahara1, J J Tesmer, A G Gilman
1Department of Pharmacology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-9041, USA.
概括
用GTPgammaS.揭示了关键信号蛋白质Gsalpha的晶体结构. 与Gialpha相比,其结构的差异解释了效应器的特异性和与信号调节器的相互作用.
科学领域:
- 结构生物学 结构生物学
- 分子生物学分子生物学
- 生物化学 生物化学
背景情况:
- Gsalpha 是一个关键的异构三级G蛋白α子单元,可激活腺酸环酶.
- 它属于GTP结合蛋白家族,以荷尔蒙依赖的方式调节效应因子活性.
研究的目的:
- 确定Gsalpha与瓜诺辛5'-O-(3-二三酸盐复合体中的晶体结构 (GTPgammaS).
- 将Gsalpha.GTPgammaS的结构与Gialpha.GTPgammaS进行比较,以了解效应器特异性.
- 阐明Gsalpha与G蛋白信号传导 (RGS) 调节器之间的相互作用的分子基础.
主要方法:
- 在2.5A分辨率的X射线晶体学.
- Gsalpha.GTPgammaS和Gialpha.GTPgammaS复合物的结构比较.
- 对Gsalpha和Gialpha之间的序列同质性和结构差异的分析.
主要成果:
- 确定了Gsalpha.GTPgammaS的晶体结构.
- 效应器的特异性主要取决于开关II螺旋和alpha3-beta5循环的结合表面形状,尽管具有高序列同质性.
- 序列分歧,而不是结构差异,解释了RGS蛋白质无法刺激Gsalpha GTPase活性.
- 贝塔马结合表面是保留的,但碳基终端螺旋和α4-β6循环的差异可能会调解受体特异性.
结论:
- 对Gsalpha的结构洞察力为了解G蛋白信号特异性提供了基础.
- 特定结构元素的差异决定了效应器和RGS相互作用,而保留区域则调解了贝塔玛子单元的结合.
- 这项研究阐明了Gsalpha如何在复杂的细胞信号通路中实现其特定功能.
相关概念视频
G-protein Coupled Receptors
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
G-protein Coupled Receptors
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
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