title: Genetic mapping of a major site of phosphorylation in adenovirus type 2 E1A proteins.
abstract: Adenovirus early region 1A (E1A) encodes two acidic phosphoproteins which are required for transactivation of viral transcription, efficient viral DNA replication in phase G0-arrested human cells, and oncogenic transformation of rodent cells. Biochemical analysis of in vivo 32P-labeled adenovirus type 2 E1A proteins purified with monoclonal antibodies demonstrated that these proteins were phosphorylated at multiple serine residues. Two-dimensional phosphotryptic peptide maps of wild-type and mutant E1A proteins were used to locate a major site of E1A protein phosphorylation at serine-219 of the large E1A protein. Although this serine fell within a consensus sequence for phosphorylation by the cyclic AMP-dependent protein kinases, experiments with mutant CHO cells defective in these enzymes indicated that it was not. Oligonucleotide-directed mutagenesis was used to substitute an alanine for serine-219. This mutation prevented phosphorylation at this site. Nonetheless, the mutant was indistinguishable from the wild type for early gene transactivation, replication on G0-arrested WI-38 cells, and transformation of cloned rat embryo fibroblast cells.
mesh_terms: D017456:Adenovirus Early Proteins; D000260:Adenoviruses, Human / Q000235:genetics*; D000409:Alanine / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002472:Cell Transformation, Viral; D006224:Cricetinae; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics* / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D010641:Phenotype; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D012694:Serine / Q000378:metabolism
chemical_list: D017456:Adenovirus Early Proteins; D009856:Oncogene Proteins, Viral; D010446:Peptide Fragments; D010750:Phosphoproteins; D012694:Serine; D011494:Protein Kinases; D000409:Alanine