DNA-dependent protein kinase in nonhomologous end joining: a lock with multiple keys?

The DNA- dependent protein kinase ( DNA- PK) is one of the central enzymes involved in DNA double- strand break ( DSB) repair. It facilitates proper alignment of the two ends of the broken DNA molecule and coordinates access of other factors to the repair complex. We discuss the latest. ndings on DNA- PK phosphorylation and offer a working model for the regulation of DNA- PK during DSB repair.