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首页> 外文期刊>Molecular and Cellular Biology >The B56α Regulatory Subunit of Protein Phosphatase 2A Is a Target for Regulation by Double-Stranded RNA-Dependent Protein Kinase PKR
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The B56α Regulatory Subunit of Protein Phosphatase 2A Is a Target for Regulation by Double-Stranded RNA-Dependent Protein Kinase PKR

机译：磷酸酶2A的B56α调节亚基是双链RNA依赖性蛋白激酶PKR调控的目标。

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PKR is a cellular serine/threonine kinase that phosphorylates eukaryotic translation initiation factor 2α (eIF2α) to regulate protein synthesis. PKR also plays a role in the regulation of transcription, programmed cell death and the cell cycle, processes which likely involve other substrates. In a yeast two-hybrid screen, we isolated human protein phosphatase 2A (PP2A) regulatory subunit B56α as a PKR-interacting protein. The interaction between B56α and PKR was confirmed by in vitro binding assays as well as by in vivo coimmunoprecipitation, and this interaction is dependent on the catalytic activity of PKR. Moreover, recombinant B56α was efficiently phosphorylated by PKR in vitro and an isoelectric point shift in B56α was detected in extracts from cells induced with the PKR activator pIC. An in vitro dephosphorylation assay showed that when B56α was phosphorylated by PKR, the activity of PP2A trimeric holoenzyme was increased. A functional interaction between B56α and PKR was observed in cotransfection assays, where a B56α-mediated increase in luciferase expression was inhibited by cotransfection with wild-type PKR. This is likely due to a decreased level of eIF4E phosphorylation caused by an increase in PP2A activity following PKR phosphorylation of B56α. Taken together, our data indicate that PKR can modulate PP2A activity by phosphorylating B56α to regulate cellular activities.
机译：PKR是一种细胞丝氨酸/苏氨酸激酶，可磷酸化真核翻译起始因子2α（eIF2α）以调节蛋白质合成。 PKR在转录调节，程序性细胞死亡和细胞周期等过程中也可能起作用，这些过程可能涉及其他底物。在酵母双杂交筛选中，我们分离了人类蛋白质磷酸酶2A（PP2A）调节亚基B56α作为PKR相互作用蛋白。 B56α和PKR之间的相互作用已通过体外结合试验以及体内共免疫沉淀法得到证实，并且这种相互作用取决于PKR的催化活性。此外，重组B56α在体外被PKR有效磷酸化，并且在PKR激活剂pIC诱导的细胞提取物中检测到B56α的等电点偏移。体外去磷酸化试验表明，当B56α被PKR磷酸化时，PP2A三聚全酶的活性增加。在共转染测定中观察到B56α和PKR之间的功能相互作用，其中与野生型PKR共转染可抑制B56α介导的萤光素酶表达增加。这可能是由于B56α的PKR磷酸化后PP2A活性增加导致eIF4E磷酸化水平降低所致。两者合计，我们的数据表明PKR可以通过磷酸化B56α调节细胞活性来调节PP2A活性。

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