CA2+ - Mediated Signal Transduction in Plants

本研究的长期目标是了解Ca2+依赖性蛋白激酶（CDPKs）在植物生长发育中的作用。CDPKs是一个新的蛋白激酶家族，它由独特的结构排列定义：在单个多肽中，激酶结构域融合到c端钙调蛋白样调节结构域。调节结构域包含4个Ca2+结合ef -手，这使得CDPKs成为Ca2+信号的主要靶标（解码器）。了解CDPKs解码和转导Ca2+信号的过程是本研究的主要重点。第一个具体目标是解决Ca2+如何激活CDPK的问题。第二个特定的目的是通过研究自抑制和Ca2+激活在全酶的机制来补充第一个。第三个具体目标是开发一种工具，该工具将允许在活细胞上使用荧光比成像来监测CDPKs的体内活性。最后，第四个特定目标是鉴定特定CDPK异构体的内源性底物。由于似乎有许多CDPK同种异构体，本研究假设每种可能具有不同的底物特异性，并且每种可能已经进化到解码不同的Ca2+信号。这项联合研究的短期目标是提出一种特定CDPK的潜在功能，来自拟南芥的AK1亚型。在植物中，钙信号参与了生长发育的许多方面，包括调节水分利用、激活植物病原体防御以及对重力的反应能力。这项研究的长期目标是了解钙离子是如何在细胞内传递信息的。这项研究是用一种模式植物系统拟南芥进行的，将有助于我们了解细胞功能的基本知识。预计这项研究将有助于探索改良农作物和做法的新方法。拟议研究的重点是新型蛋白激酶家族的结构和功能，称为CDPKs。蛋白激酶通过磷酸化修饰关键酶来调节许多细胞功能。与其他蛋白激酶不同，CDPKs直接被钙激活，使其成为钙信号的主要靶点。然而，目前尚不清楚这些激酶是如何控制细胞功能的。＊＊＊

Harper 9408108 The long range goal of this research is to understand the role of Ca2+ Dependent Protein Kinases(CDPKs)in plant growth and development. CDPKs are a novel family of protein kinases which are defined by a unique structural arrangement: Within a single polypeptide, a kinase domain is fused to a C-terminal calmodulin-like regulatory domain. The regulatory domain contains four Ca2+-binding EF-hands, which makes CDPKs a primary target (decoder) of Ca2+ signals. Understanding the process by which CDPKs decode and transduce a Ca2+ signal is the primary focus of the proposed research. The first specific aim addresses the question of how Ca2+ activates a CDPK? The second specific aim complements the first by investigating the mechanisms of autoinhibition and Ca2+ activation in the holo-enzyme. The third specific aim is to develop a tool which will permit the in vivo activity of CDPKs to be monitored using fluorescence ratio imaging on live cells. Finally, the fourth specific aim is to identify endogenous substrates for a specific CDPK isoform. Since there appear to be many CDPK isoforms, this research assumes that each may have a different substrate specificity, and that each may have evolved to decode a different Ca2+ signal. The short-term objective of this combined research is to propose a potential function for one specific CDPK, isoform AK1 from Arabidopsis. %%% In plants, calcium signals are involved in many aspects of growth and development, including regulation of water use, activation of plant pathogen defenses, and the ability to respond to gravity. The long range goal of the proposed research is to understand how calcium ions are used to communicate information within a cell. This research is being conducted with a model plant system, Arabidopsis, and will contribute to our basic knowledge of cellular function. It is anticipated that this research will be useful in exploring new approaches to improved agricultural crops and practices. The focus of the proposed research is on the structure and function of a family of novel protein kinases, called CDPKs. Protein kinases regulate many cellular functions by modifying key enzymes through phosphorylation. CDPKs, unlike any other protein kinase, are directly activated by calcium, making them primary targets of calcium signals. Nevertheless, it is not known what cellular functions are controlled by these kinases. ***