Department of Plant Biology, North Carolina State University, Raleigh, NC 27695-7649, USA.
Annu Rev Plant Biol. 2012;63:409-29. doi: 10.1146/annurev-arplant-042110-103840. Epub 2012 Jan 30.
"All things flow and change…even in the stillest matter there is unseen flux and movement." Attributed to Heraclitus (530-470 BC), from The Story of Philosophy by Will Durant. Heraclitus, a Greek philosopher, was thinking on a much larger scale than molecular signaling; however, his visionary comments are an important reminder for those studying signaling today. Even in unstimulated cells, signaling pathways are in constant metabolic flux and provide basal signals that travel throughout the organism. In addition, negatively charged phospholipids, such as the polyphosphorylated inositol phospholipids, provide a circuit board of on/off switches for attracting or repelling proteins that define the membranes of the cell. This template of charged phospholipids is sensitive to discrete changes and metabolic fluxes-e.g., in pH and cations-which contribute to the oscillating signals in the cell. The inherent complexities of a constantly fluctuating system make understanding how plants integrate and process signals challenging. In this review we discuss one aspect of lipid signaling: the inositol family of negatively charged phospholipids and their functions as molecular sensors and regulators of metabolic flux in plants.
“一切事物都在流动和变化……即使是最静止的物质也存在着看不见的流动和运动。”这句话出自赫拉克利特（公元前 530 年至公元前 470 年），出自威尔·杜兰特的《哲学的故事》。希腊哲学家赫拉克利特的思想远远超出了分子信号的范畴；然而，他富有远见的观点对今天研究信号的人来说是一个重要的提醒。即使在未受刺激的细胞中，信号通路也处于持续的代谢流动中，并提供在整个生物体中传递的基础信号。此外，带负电荷的磷脂，如多磷酸化肌醇磷脂，为吸引或排斥蛋白质提供了一个开/关开关的电路板，这些蛋白质定义了细胞的膜。这种带电荷的磷脂模板对离散变化和代谢通量很敏感，例如 pH 值和阳离子，这些变化会导致细胞中的振荡信号。由于系统不断波动的固有复杂性，理解植物如何整合和处理信号具有挑战性。在这篇综述中，我们讨论了脂质信号的一个方面：负电荷磷脂的肌醇家族及其作为植物代谢通量的分子传感器和调节剂的功能。
