Signaling Diversity Among Gqa Family Members

许多激素和神经递质依赖于Gq类异源三聚体G蛋白（Gq/11 α，G14 α和G15/16 α）在靶点发挥作用。 Gq α家族成员激活PLC β和肌醇脂质信号传导，并且建立的模型表明这些G α的细胞作用是相同的，并且是由Ca PKC途径激活引起的。 然而，现在令人信服的证据表明，Gq/11 α，G14 α和G15/16 α在它们的整体细胞反应，它们与某些蛋白质结合伴侣的相互作用以及它们的细胞和生化特性方面显着不同。 与已建立的模型相反，我的工作假设是Gq/11 α，G14 α和G15/16 α调节多个重叠和不同的信号级联，并由宿主细胞不同地调节，以引起不同的细胞反应谱。 与这一想法一致，Gqalph家族成员在不同的细胞中表达，并且Gqalpha与除了PLC β之外的多种信号传导蛋白相互作用，尽管每个结合伴侣对Gqalpha信号传导的相对贡献是未知的。 此外，Gq/11 α、G14 α和G15/16 α仅共享57%的总体氨基酸同一性，并且在它们的前35个残基（N-末端）内仅共享12%的同一性，所述前35个残基含有对于调节G α信号传导能力至关重要的脂肪酸。 虽然G14 α和G15/16 α的酰化状态是未知的，但序列比对预测Gq α家族成员的修饰不同。本论文运用现代分子、细胞和生物化学方法研究G蛋白的功能，具体目的是：1。定义存在于Gq/11 α，G14 α和G15/16 α上的对调节信号功能重要的生化修饰。2.定义调节Gq/11 α、G14 α和G15/16 α信号传导能力的因素，包括靶向亚细胞定位和与蛋白质结合伴侣的相互作用。3.确定Gq α、G14 α和G15/16 α在选定细胞中引发的细胞信号传导反应的多样性，以及Gq α结合配偶体对这些反应的相对贡献。异源三聚体G蛋白通过将细胞表面受体与细胞内反应联系起来在细胞生理学中起重要作用。 G蛋白功能障碍是越来越多的人类疾病的直接原因，目前大多数可用的药物都对G蛋白信号通路发挥作用。 这些实验将确定G蛋白的Gqalpha家族之间观察到的生化差异的功能相关性，并提供新的见解的多样性和调节这些重要的G蛋白引起的信号反应。 从这些研究中获得的信息将有助于我们更好地了解G蛋白作为治疗靶点。

Many hormones and neurotransmitters rely on the Gq class of heterotrimeric G proteins (Gq/11alpha, G14alpha, and G15/16alpha) to exert their actions at target issues. Gqalpha family members activate PLCbeta and inositol lipid signaling, and established models suggest that the cellular actions of these Galpha are identical and result from activation of Ca PKC pathways. However compelling evidence now indicated that Gq/11alpha, G14alpha, and G15/16alpha differ markedly in their overall cellular responses, their interactions with certain protein binding partners, and their cellular and biochemical properties. Contrary to established models, my working hypothesis is that Gq/11alpha, G14alpha and G15/16alpha regulate multiple overlapping and distinct signaling cascades, and are regulated differently by host cells to elicit a distinct profile of cellular responses. Consistent with this idea, Gqalph family members are expressed in different cells, and Gqalpha interacts with multiple signaling proteins besides PLCbeta, though the relative contribution of each binding partner to Gqalpha signaling is unknown. Furthermore, Gq/11alpha, G14alpha and G15/16alpha share only 57 percent overall amino acid identity, and just 12 percent identity within their first 35 residues (N- terminus) which contains fatty acids that are essential for regulating Galpha signaling capacity. Although the acylation state of G14alpha and G15/16alpha is unknown, sequence alignments predict that Gqalpha family members are modified differently. Using modem molecular, cellular, and biochemical approaches study G protein functions, the specific aims will be to: 1. Define biochemical modifications present on Gq/11alpha, G14alpha, and G15/16alpha important for regulating signaling functions. 2. Define factors that regulate Gq/11alpha, G14alpha and G15/16alpha signaling capacity including target subcelluar localization and interactions with protein binding partners. 3. Determine the diversity of cell signaling responses elicited by Gqalpha, G14alpha and G15/16alpha in selected cells, and the relative contribution of Galpha binding partners to those responses. Heterotrimeric G proteins serve essential roles in cell physiology by inking cell surface receptors to intracellular responses. G protein dysfunction is the direct cause of a growing list of human diseases, and the majority of currently available drugs exert their actions on G protein signaling pathways. These experiments will determine functional correlates for the biochemical differences observed among the Gqalpha family of G proteins, and offer new insights into the diversity and regulation of signaling responses elicited by these important G proteins. Information gained from these studies will help us to better understand G proteins as therapeutic targets.