Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia.
Plant Signal Behav. 2012 Feb;7(2):201-4. doi: 10.4161/psb.18891. Epub 2012 Feb 1.
Guanylate cyclase (GC) catalyzes the formation of cGMP and it is only recently that such enzymes have been characterized in plants. One family of plant GCs contains the GC catalytic center encapsulated within the intracellular kinase domain of leucine rich repeat receptor like kinases such as the phytosulfokine and brassinosteroid receptors. In vitro studies show that both the kinase and GC domain have catalytic activity indicating that these kinase-GCs are examples of moonlighting proteins with dual catalytic function. The natural ligands for both receptors increase intracellular cGMP levels in isolated mesophyll protoplast assays suggesting that the GC activity is functionally relevant. cGMP production may have an autoregulatory role on receptor kinase activity and / or contribute to downstream cell expansion responses. We postulate that the receptors are members of a novel class of receptor kinases that contain functional moonlighting GC domains essential for complex signaling roles.
鸟苷酸环化酶（GC）催化 cGMP 的形成，直到最近才在植物中对这种酶进行了特征描述。植物 GC 家族之一包含 GC 催化中心，该中心被包裹在富含亮氨酸重复受体样激酶的细胞内激酶结构域内，例如植物磺酸盐和油菜素甾体受体。体外研究表明，激酶和 GC 结构域都具有催化活性，这表明这些激酶-GC 是具有双重催化功能的兼职蛋白的例子。两种受体的天然配体均在分离的叶肉原生质体测定中增加细胞内 cGMP 水平，这表明 GC 活性具有功能相关性。cGMP 的产生可能对受体激酶活性具有自调控作用，和/或有助于下游细胞扩张反应。我们假设这些受体是一类新的受体激酶的成员，它们包含功能性的兼职 GC 结构域，这对于复杂的信号转导作用至关重要。
