Damage Verification and Lesion Demarcation in NER

XPG is a structure-specific endonuclease with two discernable roles in NER. It makes the incision 3 to the lesion and has nuclease activity on substrates with single/double-stranded DNA junctions mimicking the open intermediate in the NER reaction [83, 84], Prior to exerting its catalytic activity, it plays a structural role in assembling the preincision complex in NER. The presence, but not the catalytic activity of XPG is required for the assembly of the preincision complex [85, 86], 

the trimeric single-stranded DNA-binding protein that is involved in many other aspects of DNA metabolism, is believed to bind to the nondamaged strand 

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