Single-stranded structure-specific DNA endonuclease involved in DNA excision repair (  , ). Makes the 3'incision in DNA nucleotide excision repair (NER) ( , ). Binds and bends DNA repair bubble substrate and breaks base stacking at the single-strand/double-strand DNA junction of the DNA bubble . Plays a role in base excision repair (BER) by promoting the binding of DNA glycosylase NTHL1 to its substrate and increasing NTHL1 catalytic activity that removes oxidized pyrimidines from DNA . Involved in transcription-coupled nucleotide excision repair (TCR) which allows RNA polymerase II-blocking lesions to be rapidly removed from the transcribed strand of active genes . Functions during the initial step of TCR in cooperation with ERCC6/CSB to recognized stalled RNA polymerase II . Also, stimulates ERCC6/CSB binding to the DNA repair bubble and ERCC6/CSB ATPase activity . Required for DNA replication fork maintenance and preservation of genomic stability (, ). Involved in homologous recombination repair (HRR) induced by DNA replication stress by recruiting RAD51, BRCA2, and PALB2 to the damaged DNA site . During HRR, binds to the replication fork with high specificity and stabilizes it . Also, acts upstream of HRR, to promote the release of BRCA1 from DNA .
Subcellular locations: Nucleus, Chromosome
Colocalizes with RAD51 to nuclear foci in S phase . Localizes to DNA double-strand breaks (DBS) during replication stress . Colocalizes with BRCA2 to nuclear foci following DNA replication stress .