This entry represents the N-terminal domain of DNA-dependent protein kinase catalytic subunit (DNA-PKcs), which is arranged in four supersecondary alpha-helical structures, N1 to N4, that resemble HEAT repeats. Therefore, this domain is also known as N-HEAT. This domain likely mediates DNA binding and, together with the Circular Cradle, forms a ring through which Ku70/80 may present DNA for repair. DNA-PKcs is involved in DNA nonhomologous end joining (NHEJ), required for double-strand break (DSB) repair [1-4]. It is recruited by Ku70/80 heterodimer to DNA ends.

1: DNA-PKcs structure suggests an allosteric mechanism modulating DNA double-strand break repair. Sibanda BL, Chirgadze DY, Ascher DB, Blundell TL; Science. 2017;355:520-524. PMID:28154079

2: Cryo-EM structure of the DNA-PK holoenzyme. Sharif H, Li Y, Dong Y, Dong L, Wang WL, Mao Y, Wu H; Proc Natl Acad Sci U S A. 2017;114:7367-7372. PMID:28652322

3: Cryo-EM structure of human DNA-PK holoenzyme. Yin X, Liu M, Tian Y, Wang J, Xu Y; Cell Res. 2017;27:1341-1350. PMID:28840859

4: Dimers of DNA-PK create a stage for DNA double-strand break repair. Chaplin AK, Hardwick SW, Liang S, Kefala Stavridi A, Hnizda A, Cooper LR, De Oliveira TM, Chirgadze DY, Blundell TL; Nat Struct Mol Biol. 2021;28:13-19. PMID:33077952