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 (By similarity). Component of the Fanconi anemia (FA) complex. Interacts with FANCA; interaction is direct. Interacts with REV1 (By similarity). Following DNA damage, recruited to DNA interstrand cross-links (ICLs) sites by binding to ubiquitin generated by RNF8. The UBZ2-type zinc finger binds both 'Lys-48'- and 'Lys-63'-linked polyubiquitin with preference for 'Lys-63'-linked polyubiquitin.