Figure 3
From: Resolution of complex ends by non-homologous end joining - better to be lucky than good?
Joining by tolerance. The NHEJ core machinery can be associated with an XLF-XRCC4 filament that may stabilize aligned complex end structures (i) sufficiently to support transfer of the adenylate from the ligase to 5′ phosphate terminus (ii), possibly through to complete ligation (iii). If ligation aborts, the 5′ adenylated (AMP) intermediate can be removed by Aprataxin (APTX) (iv). DNA-PKcs-directed phosphorylation of XLF and XRCC4 can disrupt the XLF-XRCC4 filament (v) to allow processing factors access to the DNA to remove the obstruction.