Plant calcium-dependent protein kinase-related kinases (CRKs) do not require calcium for their activities
Plant calcium-dependent protein kinase-related kinases (CRKs) do not require calcium for their activities
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DOI：
10.1016/0014-5793(96)01090-3
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发表时间：
1996-11-04
期刊：
影响因子：
3.5
通讯作者：
Izui, K
中科院分区：
文献类型：
--
作者：
Furumoto, T;Ogawa, N;Izui, K
在植物中，钙依赖性蛋白激酶（CDPKs）组成了一个大家族，其特征是c端钙调蛋白（CaM）样结构域。最近，一种新的胡萝卜cDNA克隆编码一个非典型CDPK，其在CaM-like结构域具有明显的退化序列，并被命名为CDPK相关蛋白激酶（CRK） [Lindzen， E. and Choi， J.H. (1995) Plant Mol. Biol. 28, 785-797]。我们从玉米中获得了两个编码CRKs的cDNA克隆。在大肠杆菌中表达了一个玉米cDNA克隆，首次对CRK进行酶学表征。重组蛋白有效地磷酸化酪蛋白，一种传统的蛋白质底物。值得注意的是，在这个体外磷酸化实验中，激酶活性不需要钙作为激活剂。因此，CRKs被认为是具有退化CaM结构域的新型钙非依赖性蛋白激酶，其功能仍有待阐明。
In plants, calcium-dependent protein kinases (CDPKs) make up a large family that is characterized by a C-terminal calmodulin(CaM)-like domain. Recently, a novel carrot cDNA clone encoding an atypical CDPK, which has a significantly degenerate sequence in the CaM-like domain, was found and named CDPK-related protein kinase (CRK) [Lindzen, E. and Choi, J.H. (1995) Plant Mol. Biol. 28, 785-797]. We obtained two different cDNA clones from maize which encode CRKs. For the first enzymatic characterization of CRK, a maize cDNA clone was expressed in E. coli. The recombinant protein efficiently phosphorylated casein, a conventional protein substrate. Notably, in this in vitro phosphorylation assay, the kinase activity did not require calcium as an activator. Thus, CRKs were suggested to be novel calcium-independent protein kinases having a degenerate CaM domain, the function of which remains to be elucidated.