G Protein signaling at the endosome

内体中的 G 蛋白信号传导

• 批准号: 7425534
• 负责人: Henrik G. Dohlman
• 金额: $ 5.34万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7425534
• 关键词: 1-Phosphatidylinositol 3-Kinase; Affinity; Binding; Binding Proteins; Cell Surface Receptors; Cell membrane; Cell surface; Cells; Characteristics; Complex; Copper; Cytoplasm; Dissociation; Employee Strikes; Endosomes; Eukaryota; Eukaryotic Cell; Event; Figs - dietary; Fungal Genome; G Beta Gamma; G-Protein-Coupled Receptors; GTP Binding; GTP-Binding Protein alpha Subunits, Gs; GTP-Binding Proteins; Green Fluorescent Proteins; Guanine Nucleotide Exchange Factors; Guanine Nucleotides; Guanosine Triphosphate Phosphohydrolases; Hormones; Human; Intracellular Second Messenger; Link; Maps; Mediating; Mitogen-Activated Protein Kinases; Modeling; Molecular Conformation; Monitor; Neurotransmitters; Partner in relationship; Pathway interactions; Pheromone; Pheromone Receptors; Phosphatidylinositols; Phospholipids; Phosphotransferases; Physiological; Point Mutation; Production; Protein Overexpression; Proteins; Recruitment Activity; Relative (related person); Research Personnel; Role; Second Messenger Systems; Series; Signal Pathway; Signal Transduction; Signaling Molecule; Signaling Protein; Site; Structure; System; Testing; Transducers; Ursidae Family; WD Repeat; Yeasts; human disease; hypertension treatment; mutant; nervous system disorder; novel; phosphatidylinositol 3-phosphate; programs; protein function; receptor; receptor binding; research study; response; rho; second messenger; yeast protein

Most hormones and neurotransmitters bind to cell surface receptors, activate G proteins, and produce a second messenger that propagates the signal within the cell. In yeast the G-beta/gamma subunits are necessary and sufficient for most aspects of the response to mating pheromones. Recently however,we determined that the G-alpha protein (Gpa1) can also transmit a signal mediated by the only known phosphatidylinositol 3-kinase in yeast (Vps34) and the phospholipid second messenger, Ptdlns 3-P. Notably, Gpa1 and Vps34 are both located at the endosome, far removed from receptors and the G-beta/gamma subunits. Our objective in this proposal is to identify other components of the pathway (receptor, G- beta/gamma, effector target) and the mechanism by which these proteins transmit their signal at the endosome. There are three specific aims: Aim 1. How is the G protein at the endosome activated? We have shown that Gpa1 stimulates Vps34 and Ptdlns 3-P production at the endosome but we do not know how Gpa1 is activated in this case. Our hypothesis is that Gpa1 and Vps34 are activated by internalized pheromone receptors and subsequently by a second exchange factor at the endosome. Aim 2. What are the G-beta/gamma-like proteins at the endosome? We found that the Ptdlns 3-kinase regulatory subunit Vps15 has a 7-WD repeat domain structure typical of that found in G-beta proteins. Our hypothesis is that Vps15 functions as the G-beta subunit at the endosome. Aim 3. How is G protein signaling at the endosome transmitted? We have shown that the Ptdlns 3-P- binding protein Bem1 translocates to the endosome in response to Gpa1 activation. Our hypothesis is that Ptdlns 3-P activates Bem1 and recruits a subset of signaling proteins to the endosome. These findings reveal a surprising new role and a new site of action for this well-characterized signaling molecule. Mechanisms discovered in yeast are usually recapitulated in higher eukaryotes, so the principles elucidated here will likely apply as well to hormone and neurotransmitter function in humans. Just as G protein coupled receptors at the cell surface are proven targets for the treatment of hypertension and diverse neurological disorders, intracellular receptors are likely as well to be useful in treating human disease.

大多数激素和神经递质与细胞表面受体结合，激活G蛋白，并产生 在细胞内传播信号的第二信使。在酵母中，G-β/伽马亚基是 对于交配信息素的反应的大多数方面来说是必要的和充分的。然而，最近，我们 确定G-α蛋白(Gpa1)也可以传递由唯一已知的 酵母中的磷脂酰肌醇3-激酶(Vps34)和磷脂第二信使Ptdlns 3-P。值得注意的是， Gpa1和Vps34都位于内吞体内，远离受体和G-β/γ 亚单位。我们在这项建议中的目标是确定该途径的其他组成部分(受体，G- β/伽马，效应靶)以及这些蛋白质在 内生体。具体目标有三个： 目的1.内吞体内的G蛋白是如何被激活的？我们已经证明Gpa1刺激Vps34和 Ptdlns 3-P在内体产生，但我们不知道Gpa1在这种情况下是如何激活的。我们的 假设Gpa1和Vps34被内化的信息素受体激活，随后通过 内体的第二个交换因子。 目的2.内吞体内的G-β/伽马样蛋白是什么？我们发现Ptdlns 3-激酶 调节亚基Vps15具有典型的G-β蛋白的7-WD重复结构域结构。我们的 假设Vps15在内吞体内起G-β亚基的作用。 目的3.G蛋白是如何在内体传递信号的？我们已经证明了Ptdlns 3-P- 结合蛋白Bem1在Gpa1激活后转位到内体。我们的假设是 Ptdlns 3-P激活Bem1，并将信号蛋白的一个子集招募到内体。 这些发现揭示了一个令人惊讶的新角色和一个新的作用场所，这一特征很好的信号 分子。在酵母中发现的机制通常在高等真核生物中重现，所以原理 这里阐明的可能也适用于人类的激素和神经递质功能。就像G 细胞表面的蛋白偶联受体是治疗高血压和多种疾病的有效靶点 神经性疾病、细胞内受体也可能在治疗人类疾病方面有用。