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

作者：Akira Suwa, M. Hirakata, Yoshihiko Takeda, Stephen A. Jesch, Tatsuyuki Mimori, John Hardin · 发表于：Proceedings of the National Academy of Sciences · 年份：1994 · DOI：10.1073/pnas.91.15.6904 · 被引用次数：170 · 研究领域：Monoclonal and Polyclonal Antibodies Research、RNA and protein synthesis mechanisms、Glycosylation and Glycoproteins Research

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.