title: Adenovirus E4orf4 protein binds to protein phosphatase 2A, and the complex down regulates E1A-enhanced junB transcription.
abstract: 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.
authors.affiliation: Department of Molecular Biology, Howard Hughes Medical Institute, Princeton University, New Jersey 08544-1014.
authors.forename: T
authors.initials: T
authors.lastname: Kleinberger
authors.forename: T
authors.initials: T
authors.lastname: Shenk
mesh_terms: D017500:Adenovirus E1A Proteins / Q000378:metabolism*; D017504:Adenovirus E4 Proteins / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D015536:Down-Regulation; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D054648:Protein Phosphatase 2; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis* / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D017500:Adenovirus E1A Proteins; D017504:Adenovirus E4 Proteins; D046911:Macromolecular Substances; D016755:Proto-Oncogene Proteins c-jun; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2