title: Autoantibodies to DNA-dependent protein kinase. Probes for the catalytic subunit.
abstract: DNA-dependent protein kinase (DNA-PK) is an important nuclear enzyme which consists of a catalytic subunit known as DNA-PKcs and a regulatory component identified as the Ku autoantigen. In the present study, we surveyed 312 patients in a search for this specificity. 10 sera immunoprecipitated a large polypeptide which exactly comigrated with DNA-PKcs in SDS-PAGE. Immunoblot analysis demonstrated that this polypeptide was recognizable by a rabbit antiserum specific for DNA-PKcs. Although the patient sera did not bind to biochemically purified DNA-PKcs in immunoblots or ELISA, they were able to deplete DNA-PK catalytic activity from extracts of HeLa cells in a dose-dependent manner. We conclude that these antibodies should be useful probes for studies which aim to define the role of DNA-PK in cells. Since six sera simultaneously contained antibodies to the Ku protein, these studies suggest that relatively intact forms of DNA-PK complex act as autoantigenic particles in selected patients.
authors.affiliation: Department of Medicine, Medical College of Georgia School of Medicine, Augusta, 30912-3100, USA.
authors.forename: A
authors.initials: A
authors.lastname: Suwa
authors.forename: M
authors.initials: M
authors.lastname: Hirakata
authors.forename: Y
authors.initials: Y
authors.lastname: Takeda
authors.forename: Y
authors.initials: Y
authors.lastname: Okano
authors.forename: T
authors.initials: T
authors.lastname: Mimori
authors.forename: S
authors.initials: S
authors.lastname: Inada
authors.forename: F
authors.initials: F
authors.lastname: Watanabe
authors.forename: H
authors.initials: H
authors.lastname: Teraoka
authors.forename: W S
authors.initials: WS
authors.lastname: Dynan
authors.forename: J A
authors.initials: JA
authors.lastname: Hardin
mesh_terms: D034961:Antigens, Nuclear; D001323:Autoantibodies / Q000276:immunology* / Q000302:isolation & purification; D004265:DNA Helicases; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006367:HeLa Cells; D006801:Humans; D000072200:Ku Autoantigen; D009687:Nuclear Proteins / Q000276:immunology; D017346:Protein Serine-Threonine Kinases / Q000276:immunology*
chemical_list: D034961:Antigens, Nuclear; D001323:Autoantibodies; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen