Scaffold protein involved in DNA single-strand break repair by mediating the assembly of DNA break repair protein complexes (PubMed:11163244, PubMed:28002403). Negatively regulates ADP- ribosyltransferase activity of PARP1 during base-excision repair in order to prevent excessive PARP1 activity (PubMed:28002403, PubMed:34102106, PubMed:34811483). Recognizes and binds poly-ADP-ribose chains: specifically binds auto-poly-ADP-ribosylated PARP1, limiting its activity (PubMed:14500814, PubMed:34102106, PubMed:34811483). {ECO:0000269|PubMed:11163244, ECO:0000269|PubMed:14500814, ECO:0000269|PubMed:28002403, ECO:0000269|PubMed:34102106, ECO:0000269|PubMed:34811483}. This is the function of XRCC1 (X-ray repair cross complementing 1, ENSG00000073050).