title: Identification of a phosphorylation site in c-Ski as serine 515.
abstract: c-Ski has been known to be phosphorylated at serine residue(s), which results in slower migration of c-Ski in SDS-polyacrylamide gel electrophoresis. The position(s) of phosphorylation, however, has not been determined. In the present study, we identified a phosphorylation site of c-Ski which affects its electrophoretic motility as serine 515 using MALDI-TOF mass spectrometry. A phosphorylation-resistant mutant, c-Ski S515A, did not exhibit a phosphatase-sensitive band shift. In addition, we confirmed that endogenous c-Ski is phosphorylated at serine 515, using a specific antibody. The phosphorylation status of c-Ski, however, does not appear to affect its stability or effects on TGF-β signalling. Identification of the phosphorylation site of c-Ski would allow us further examination of physiological significance of c-Ski phosphorylation.
authors.affiliation: Department of Molecular Pathology, Graduate School of Medicine, University of Tokyo, Japan.
authors.forename: Motoko
authors.initials: M
authors.lastname: Nagata
authors.forename: Shinji
authors.initials: S
authors.lastname: Nagata
authors.forename: Keiko
authors.initials: K
authors.lastname: Yuki
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Isogaya
authors.forename: Masao
authors.initials: M
authors.lastname: Saitoh
authors.forename: Kohei
authors.initials: K
authors.lastname: Miyazono
authors.forename: Keiji
authors.initials: K
authors.lastname: Miyazawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D016212:Transforming Growth Factor beta; C060614:SKI protein, human; D012694:Serine