Abstract
Non-homologous end-joining (NHEJ) is crucial for repair of DNA double-strand breaks. This pathway is processed through the catalytic joining of DNA ends by the complex of DNA ligase IV and XRCC4. In addition, this process is regulated by DNA-dependent serine/threonine protein kinase (DNA-PK) components, including a large catalytic subunit (DNA-PKcs) and a DNA-binding complex of Ku70 and Ku86 subunits known as the Ku autoantigen. The function of the DNA-PK complex remains to be fully defined in the context of the end-joining reaction. To obtain biochemical evidence about this issue, we attempted to separate and characterize of a DNA-PK mediated DNA end-joining activity from human placenta, which has a high amount of DNA-PK components and a moderate level of the end-joining activity. Here we demonstrated the valid scheme for separation of the end-joining activity that is regulated by DNA-PK activity, whose inhibitor, wortmannin, simultaneously suppresses the end-joining activity. [J Radiat Res 44:437 (2003)]
