Autoantibodies to DNA-dependent protein kinase. Probes for the catalytic subunit.
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.
Suwa
A
A
Department of Medicine, Medical College of Georgia School of Medicine, Augusta, 30912-3100, USA.
Hirakata
M
M
Takeda
Y
Y
Okano
Y
Y
Mimori
T
T
Inada
S
S
Watanabe
F
F
Teraoka
H
H
Dynan
W S
WS
Hardin
J A
JA
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*
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