Kleinberger T, Shenk T
Department of Molecular Biology, Howard Hughes Medical Institute, Princeton University, New Jersey 08544-1014.
J Virol. 1993 Dec;67(12):7556-60. doi: 10.1128/JVI.67.12.7556-7560.1993.
Adenovirus E4orf4 protein was previously shown to counteract transactivation of junB by cyclic AMP (cAMP) and E1A protein. It was also shown to cause hypophosphorylation of E1A and c-Fos proteins. Here we show that the E4orf4 protein associates with protein phosphatase 2A. All three subunits of the phosphatase are present in the complex, and the B subunit interacts directly with the viral protein. The complex possesses a phosphatase activity typical of protein phosphatase 2A, and the phosphatase mediates the E4orf4-induced down regulation of junB transcription. Thus, adenovirus E4orf4 protein recruits protein phosphatase 2A into a signal transduction pathway initiated by cAMP and E1A protein.
腺病毒E4orf4蛋白先前已被证明可对抗环磷酸腺苷（cAMP）和E1A蛋白对junB的反式激活作用。它还被证明可导致E1A和c-Fos蛋白的低磷酸化。在此我们表明，E4orf4蛋白与蛋白磷酸酶2A相关联。该磷酸酶的所有三个亚基都存在于复合物中，并且B亚基直接与病毒蛋白相互作用。该复合物具有蛋白磷酸酶2A典型的磷酸酶活性，并且该磷酸酶介导E4orf4诱导的junB转录下调。因此，腺病毒E4orf4蛋白将蛋白磷酸酶2A募集到由cAMP和E1A蛋白启动的信号转导途径中。
