Figure 3.

Homology- and non-homology-directed DSB repair. NHEJ is driven by the DNA-PKcs axis and re-joins two broken ends directly which usually leads to small DNA sequence deletions. Conversely, error-free HR involves extensive end resection generating 3′ single-stranded DNA tracts that are coated by RPA and subsequently displaced during Rad51-mediated strand invasion of a homologous DNA duplex. After D-loop extension, HR intermediates are mostly resolved through synthesis-dependent strand annealing (SDSA); however, in some cases double Holliday junction (dHJ) resolvases or dissolution is required resulting in crossover or non-crossover products, respectively.