PCaPs, possible regulators of PtdInsP signals on plasma membrane
PCaPs, possible regulators of PtdInsP signals on plasma membrane
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DOI：
10.4161/psb.5.7.11825
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发表时间：
2010-01-01
影响因子：
2.9
通讯作者：
Maeshima, Masayoshi
中科院分区：
文献类型：
--
作者：
Kato, Mariko;Nagasaki-Takeuchi, Nahoko;Maeshima, Masayoshi
在植物中，Ca2+、磷酸磷脂酰肌醇（PtdInsPs）和磷酸肌醇是细胞内信号传导的主要成分。几种蛋白质和酶，如钙调蛋白（CaM）、蛋白激酶、蛋白磷酸酶和Ca2+通道，介导信号传导。从拟南芥中鉴定出两个新的Ca2+结合蛋白，命名为PCaP1和PCaP2[质膜（PM）相关Ca2+（阳离子）结合蛋白1和2]。PCaP1在中心和c端部分有一个内在无序的区域。PCaP1基因在大多数组织中表达，PCaP2基因主要在根毛和花粉管中表达。我们最近证明了这些蛋白是n -肉豆酰化的，稳定地锚定在PM中，并与磷脂酰肌醇磷酸结合，特别是PtdInsP(2)s。在这里，我们提出了一个由ptdinsp介导的Ca2+信号转换机制模型。当胞浆中游离Ca2+增加时，Ca2+与CaM （Ca2+CaM）形成复合物。PCaPs与Ca2+-CaM结合导致PCaPs释放PtdInsPs。在ptdinsp释放之前，信号一直处于静止状态。
In plants, Ca2+, phosphatidylinositol phosphates (PtdInsPs) and inositol phosphates are major components of intracellular signaling. Several kinds of proteins and enzymes, such as calmodulin (CaM), protein kinase, protein phosphatase, and the Ca2+ channel, mediate the signaling. Two new Ca2+-binding proteins were identified from Arabidopsis thaliana and named PCaP1 and PCaP2 [plasma membrane (PM)-associated Ca2+(cation)-binding protein 1 and 2]. PCaP1 has an intrinsically disordered region in the central and C-terminal parts. The PCaP1 gene is expressed in most tissues and the PCaP2 gene is expressed predominantly in root hairs and pollen tubes. We recently demonstrated that these proteins are N-myristoylated, stably anchored in the PM, and are bound with phosphatidylinositol phosphates, especially PtdInsP(2)s. Here we propose a model for the switching mechanism of Ca2+-signaling mediated by PtdInsPs. Ca2+ forms a complex with CaM (Ca2+CaM) when there is an increase in the cytosol free Ca2+. The binding of PCaPs with Ca2+-CaM causes PCaPs to release PtdInsPs. Until the release of PtdInsPs, the signaling is kept in the resting state.