Constituent of the CeBCD complex that possesses E3 ubiquitin-protein ligase activity (PubMed:16628214). When bound to chromatin, the brc-1-brd-1 heterodimer within the CeBCD complex is inactive during normal conditions, but in response to DNA damage, the brc-1-brd-1 heterodimer associates with other proteins such as the recombinase rad-51 or the E2-ubiquitin-conjugating enzyme let-70, which activate the CeBCD complex as an E3-ubiquitin ligase (PubMed:16628214). Moreover, association between the brc-1-brd-1 heterodimer and rad-51 and let-70, probably requires DNA checkpoint proteins such as atl-1 and mre-11 in order to induce ubiquitination at DNA damage sites (PubMed:16628214). To this end, the brc-1-brd-1 heterodimer coordinates a diverse range of cellular pathways such as DNA damage repair, ubiquitination and transcriptional regulation to maintain genomic stability (PubMed:14711411, PubMed:30383754). Plays a role in triggering cellular responses at damage sites in response to DNA damage that may be induced by ionizing radiation for example (PubMed:14711411, PubMed:30383754). In particular, protects against chromosome non-disjunction and nuclear fragmentation during meiotic double-strand break repair to ensure sister chromatid recombination and aid chromosome stability (PubMed:14711411). S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. E3 ubiquitin-protein ligase activity of CeBCD complexes occurs at DNA damage sites. Following DNA damage, E3 ubiquitin-protein ligase activity is reduced by caffeine treatment (inhibitor of ATM and ATK kinase activity). Protein modification; protein ubiquitination. Heterodimer (via RING-type zinc finger) with brc-1 to form the core CeBCD complex (PubMed:16628214). Brc-1-brd-1 heterodimer-containing CeBCD complexes bound to chromatin are activated as an E3-ubiquitin ligase in response to DNA damage (PubMed:16628214). The heterodimer interacts with the recombinase rad-51 following ionizing irradiation; the interaction is direct (PubMed:16628214). The heterodimer interacts the E2-ubiquitin-conjugating enzyme let-70 following ionizing irradiation (PubMed:16628214). The heterodimer interacts with the pro-crossover proteins msh-5 and syp-3 (PubMed:30383754). Interacts with smt-3, tac-1 and ubc-9 (PubMed:14711411). Co-localizes with brc-1 in germline nuclei at meiotic prophase I (PubMed:30383754). At the transition between mid- and late- pachytene, localization together with brc-1 is less diffuse and becomes a linear pattern along the chromosomes (PubMed:30383754). In late pachytene nuclei, co-localizes with brc-1 at crossover sites and the short arm of homologous chromosomes (PubMed:30383754). Autoubiquitinated. Phosphorylation of CeBCD complexes is required for E3 ubiquitin-protein ligase activity. DNA damage repair defects following ionizing radiation with reduced ubiquitination at DNA damage sites (PubMed:16628214). RNAi-mediated knockdown results in elevated levels of chromosome non-disjunction that manifest as a high incidence of males, impaired progeny survival and chromosome fragmentation after irradiation and elevated levels of p53-dependent germ cell death before and after irradiation (PubMed:14711411). Absence of S-phase checkpoint function.