Characterisation of two protein phosphatase 2A holoenzymes from maize seedlings
Characterisation of two protein phosphatase 2A holoenzymes from maize seedlings
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DOI：
10.1016/s0167-4838(00)00097-2
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发表时间：
2000-07-14
期刊：
影响因子：
--
通讯作者：
Muszynska, G
中科院分区：
文献类型：
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作者：
Awotunde, OS;Sugajska, E;Muszynska, G
从玉米幼苗中分离纯化了两种蛋白磷酸酶2A（PP 2A）全酶，命名为PP 2AI和PP 2AII。玉米全酶的亚基组成一般类似于动物PP 2A。使用SDS/PAGE和Western印迹与抗体产生的肽来自动物PP 2A，我们建立了植物蛋白磷酸酶2A的亚基组成。在两种玉米全酶中，存在一个38000的催化亚基（PP 2Ac）和一个66000的恒定调节亚基（A），构成PP 2A的核心二聚体。此外，PP 2AI（180 000-200 000）含有一个57 000的蛋白质，该蛋白质与针对所有真核B α调节亚基中保守的肽（EFDYLKSLEIEE）产生的抗体反应。相比之下，通过双重染色在PP 2AII（140 000-160 000）中可见的蛋白质均不与这些抗体反应。在鱼精蛋白和硫酸铵存在下，用P-32-标记的磷酸化酶a测量的PP 2AI的活性比PP 2AII的活性高约两倍。PP 2AI和PP 2AII显示出不同的激活模式，鱼精蛋白，多聚赖氨酸和组蛋白H1，并表现出高敏感性对抑制冈田酸。所获得的数据提供了直接的生化证据的存在，在植物中的PP 2A全酶组成的催化亚基与一个或两个调节亚基复合。(C)2000 Elsevier Science B. V.保留所有权利。
Two holoenzymes of protein phosphatase 2A (PP2A), designated PP2AI and PP2AII, were purified from maize seedlings. The subunit composition of maize holoenzymes generally resembled those of animal PP2A. Using SDS/PAGE and Western blots with antibodies generated against peptides derived from animal PP2A, we established the subunit composition of plant protein phosphatase 2A. In both maize holoenzymes, a 38 000 catalytic (PP2Ac) and a 66 000 constant regulatory subunit (A) constituting the core dimer of PP2A were present. In addition, PP2AI (180 000-200 000) contained a protein of 57 000 which reacted with antibodies generated against the peptide (EFDYLKSLEIEE) conserved in all eukaryotic B alpha regulatory subunits. In contrast, none of the proteins visualised in PP2AII (140 000-160 000) by double staining reacted with these antibodies. The activity of PP2AI measured with P-32-labelled phosphorylase a in the presence of protamine and ammonium sulfate is about two times higher than that of PP2AII. PP2AI and PP2AII displayed different patterns of activation by protamine, polylysine and histone H1 and exhibit high sensitivity toward inhibition by okadaic acid. The data obtained provide direct biochemical evidence for the existence in plants of PP2A holoenzymes composed of a catalytic subunit complexed with one or two regulatory subunits. (C) 2000 Elsevier Science B.V. All rights reserved.