P38398 · Chains A, B, C, D
Breast cancer type 1 susceptibility protein
Homo sapiens
E3 ubiquitin-protein ligase that specifically mediates the formation of 'Lys-6'-linked polyubiquitin chains and plays a central role in DNA repair by facilitating cellular responses to DNA damage [1–7]. It is unclear whether it also mediates the formation of other types of polyubiquitin chains [3]. The BRCA1-BARD1 heterodimer coordinates a diverse range of cellular pathways such as DNA damage repair, ubiquitination and transcriptional regulation to maintain genomic stability [3, 4, 8].
Regulates centrosomal microtubule nucleation [9]. Required for appropriate cell cycle arrests after ionizing irradiation in both the S-phase and the G2 phase of the cell cycle [10, 11, 12, 7]. Required for FANCD2 targeting to sites of DNA damage [2].
Inhibits lipid synthesis by binding to inactive phosphorylated ACACA and preventing its dephosphorylation [13]. Contributes to homologous recombination repair (HRR) via its direct interaction with PALB2, fine-tunes recombinational repair partly through its modulatory role in the PALB2-dependent loading of BRCA2-RAD51 repair machinery at DNA breaks [14]. Component of the BRCA1-RBBP8 complex which regulates CHEK1 activation and controls cell cycle G2/M checkpoints on DNA damage via BRCA1-mediated ubiquitination of RBBP8 [5].
Acts as a transcriptional activator [15]
UniProt · P38398 · Snapshot 10/11/2026