title: Analysis of phosphorylation sites in the exon 1 region of E1A proteins of human adenovirus type 5.
abstract: Early region 1A (E1A) of human adenovirus type 5 (Ad5) produces five mRNAs that encode proteins of 55, 171, 217, 243, and 289 residues. We have shown previously that the major products of 289 and 243 residues are phosphorylated at a minimum of three sites of which one, Ser-89, is located in the amino terminal half of the protein. In the present report we show that these E1A proteins are also phosphorylated at a second site in this region located at Ser-96. The 171 and 217 residue E1A species were also tentatively identified and, as predicted, neither contained the Ser-89 or Ser-96 sites but both appeared to be phosphorylated at the same sites as 289R and 243R toward the carboxy terminus. Studies with mutants in which Ser-89 or Ser-96 were converted to alanine residues indicated that phosphorylation of Ser-89 but not Ser-96 induces the major shift in gel mobility of E1A products. However, neither site appears to be of major importance in the regulation of E1A-mediated transactivation or transformation.
authors.affiliation: Department of Pathology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: M L
authors.initials: ML
authors.lastname: Tremblay
authors.forename: D J
authors.initials: DJ
authors.lastname: Dumont
authors.forename: P E
authors.initials: PE
authors.lastname: Branton
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D017456:Adenovirus Early Proteins; D000260:Adenoviruses, Human / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D008970:Molecular Weight; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D010449:Peptide Mapping; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D013329:Structure-Activity Relationship; D014357:Trypsin
chemical_list: D017456:Adenovirus Early Proteins; D009856:Oncogene Proteins, Viral; D012333:RNA, Messenger; D010768:Phosphoserine; D000135:Acid Phosphatase; D014357:Trypsin