INTERACTIONS BETWEEN THE SUBUNITS OF CASEIN KINASE-II
INTERACTIONS BETWEEN THE SUBUNITS OF CASEIN KINASE-II
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DOI：
10.1074/jbc.270.22.13017
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发表时间：
1995-06-02
影响因子：
4.8
通讯作者：
LITCHFIELD, DW
中科院分区：
文献类型：
--
作者：
GIETZ, RD;GRAHAM, KC;LITCHFIELD, DW
酪蛋白激酶II(Casein Kinase II，CKII)是一种蛋白丝氨酸/苏氨酸激酶，控制着多种调节核蛋白的活性。该酶具有由两个催化(α和/或α‘)亚基和两个β亚基组成的四聚体结构。我们用α、α‘或β亚基特异性抗体通过免疫沉淀法检测了纯化的牛CKII四聚体复合体的亚基组成。这些实验表明，该酶可以以同源异构体(即α(2)β(2)α(2)‘β(2))和异构体(即α’β(2))的形式存在。为了进一步研究CKII的α、α‘或β亚基之间的亚基相互作用，我们利用了酵母双杂交系统(Fields，S.和Song，O.(1989)Natural 340：245-246)。在这些研究中，人CKII的每个亚基在酵母中以与DNA结合域或酵母GAL4转录激活域的转录激活域融合的形式在酵母中表达。这些研究表明，CKII的α或α‘亚基可以与CKII的β亚基相互作用，但不能与其他α或α’亚基相互作用。相比之下，CRII的β亚基可以与α、α‘或β亚基相互作用。这些结果表明，CKII全酶的形成是由于β亚基的二聚化能力，使两个异二聚体(αβ或α‘β)形成四聚体复合体。
Casein kinase II (CKII) is a protein serine/threonine kinase known to control the activity of a variety of regulatory nuclear proteins. This enzyme has a tetrameric structure composed of two catalytic (alpha and/or alpha') subunits and two beta subunits. We have examined the subunit composition of tetrameric complexes of purified bovine CKII by immunoprecipitation using alpha, alpha', or beta subunit-specific antibodies. These experiments indicate that the enzyme can exist as homotetramers (i.e. alpha(2) beta(2) alpha(2)'beta(2)) as well as heterotetramers (i.e. alpha alpha'beta(2),). To further examine subunit interactions between the alpha, alpha', or beta subunits of CKII, we have utilized the yeast two hybrid system (Fields, S. and Song, O. (1989) Nature 340: 245-246). For these studies, each subunit of human CKII was expressed in yeast as a fusion with the DNA binding domain or with the transcriptional activation domain of the yeast GAL4 transcriptional activator. These studies demonstrate that the alpha or alpha' subunits of CKII can interact with the beta subunits of CKII, but not with other alpha or alpha' subunits. By comparison, the beta subunits of CRII can interact with alpha, alpha', or beta subunits. These results indicate that the CKII holoenzyme forms because of the ability of beta subunits to dimerize, bringing two heterodimers (alpha beta or alpha'beta) into a tetrameric complex.