E3 ubiquitin-protein ligase that specifically mediates the formation of polyubiquitin chains and plays a central role in DNA repair (PubMed:16628214). Plays a role in triggering cellular responses at damage sites in response to DNA damage that may be induced by UV and ionizing radiation for example (PubMed:14711411, PubMed:16628214, PubMed:24424777, PubMed:26903030, PubMed:30383754). Functions in double-strand break repair, and is required for homologous recombination between sister chromatids in meiotic and mitotic cells (PubMed:18219312, PubMed:19646877, PubMed:24424777, PubMed:26903030). 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, PubMed:18219312, PubMed:24424777). Required for normal cell cycle progression (PubMed:20207739). Along with brap-2 modulates the expression of cell cycle arrest protein cki-1 in response to increased levels of reactive oxygen species (PubMed:20207739). Constituent of the CeBCD complex that possesses E3 ubiquitin-protein ligase activity (PubMed:14711411). 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). 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 brd-1 to form the core CeBCD complex (PubMed:14711411, 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). Mainly localizes to the nucleus and a small proportion is chromatin bound (PubMed:30383754). Co-localizes with brd-1 in germline nuclei at meiotic prophase I (PubMed:30383754). At the transition between mid- and late- pachytene, localization together with brd-1 is less diffuse and becomes a linear pattern along the chromosomes (PubMed:30383754). In late pachytene nuclei, co-localizes with brd-1 and syp-1 at crossover sites and the short arm of the bivalent (PubMed:30383754). Co-localizes with the pro-crossover factors cosa-1, zhp-3 and msh-5 at crossover sites in mid-late pachytene nuclei (PubMed:30383754). Co-localizes with plk-2 in pachytene nuclei (PubMed:30383754). Localizes to DNA damage sites on chromatin following DNA damage. Phosphorylation of CeBCD complexes is required for E3 ubiquitin-protein ligase activity. Animals are viable (PubMed:18219312, PubMed:19646877). However, there is defective double strand break repair (PubMed:18219312, PubMed:19646877, PubMed:26903030). During the early stages of meiosis, this is characterized by impaired homologous recombination in germ cells with increased apoptosis and increased numbers of rad-51-positive foci (PubMed:18219312, PubMed:19646877). Increased sensitivity to UV and IR irradiation and topoisomerase inhibitor camptothecin compared to wild-type (PubMed:24424777, PubMed:26903030). Following either IR irradiation or camptothecin treatment, there is reduced egg hatching (PubMed:26903030). Furthermore, there are also DNA damage repair defects following ionizing radiation and UV irradiation characterized by reduced ubiquitination at DNA damage sites and reduced rad-51-positive foci, respectively (PubMed:16628214, PubMed:24424777, PubMed:26903030). High levels of embryonic lethality and abolished brd-1 expression following DNA damage induced by ionising radiation (PubMed:30383754). Double knockout with brd-1 impairs rad-51 localization to DNA damage sites following DNA damage induced by ionising radiation (PubMed:30383754). RNAi-mediated knockdown results in high X chromosome non-disjunction leading to a high incidence of males (him) phenotype (PubMed:14711411). RNAi-mediated knockdown in addition to gamma-irradiation at the L4 stage of larval development, results in reduced progeny, increased cep-1/p53-dependent germ cell death, chromosome fragmentation and DNA repair defects (PubMed:14711411).