DNA-dependent protein kinase (Ku protein-p350 complex) assembles on double-stranded DNA

Akira Suwa, Michito Hirakata, Yoshihiko Takeda, Stephen A. Jesch, Tsuneyo Mimori, John A. Hardin

Research output: Contribution to journalArticlepeer-review

173 Scopus citations


The Ku protein is an autoantigen that consists of 70- and 80-kDa polypeptides. It associates with double-stranded DNA at free ends. In the present study, we examined the ability of anti-Ku antibodies to immunoprecipitate various structures from extracts of HeLa cells prepared at different salt concentrations. Under physiological conditions, these antibodies identified a complex containing the Ku protein and the 350-kDa component (p350) of DNA-dependent protein kinase (DNA-PK), which appeared to be closely associated on the DNA strand. In reconstitution experiments with cell extracts and biochemically purified components, the Ku protein-p350 complex formed only in the presence of double-stranded DNA. The reconstituted complex was catalytically active. Together with previous studies, these results indicate that the Ku protein interacts with DNA to create a binding site for p350 as the DNA-PK holoenzyme assembles.

Original languageEnglish (US)
Pages (from-to)6904-6908
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number15
StatePublished - Jul 19 1994
Externally publishedYes


  • human autoantigen Ku
  • transcription factor

ASJC Scopus subject areas

  • General


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