Component of the Fanconi anemia (FA) complex required to recruit the FA complex to DNA interstrand cross-links (ICLs) and promote ICLs repair. Following DNA damage recognizes and binds 'Lys- 63'-linked ubiquitin generated by RNF8 at ICLs and recruits other components of the FA complex. Promotes translesion synthesis via interaction with REV1. {ECO:0000269|PubMed:22266823, ECO:0000269|PubMed:22343915, ECO:0000269|PubMed:22396592, ECO:0000269|PubMed:22705371}. This is the function of Ensembl gene identifier ENSG00000162585 (FAAP20, FA core complex associated protein 20).