RING finger, HC subclass, found in BRCA1-associated RING domain protein 1 (BARD-1) and similar proteins
BARD-1 is a critical factor in BRCA1-mediated tumor suppression and may also serve as a target for tumorigenic lesions in some human cancers. It associates with BRCA1 (breast cancer-1) to form a heterodimeric BRCA1/BARD1 complex that is responsible for maintaining genomic stability through nuclear functions involving DNA damage signaling and repair, transcriptional regulation, and cell cycle control. The BRCA1/BARD1 complex catalyzes autoubiquitination of BRCA1 and trans ubiquitination of other protein substrates. Its E3 ligase activity is dramatically reduced in the presence of UBX domain protein 1 (UBXN1). BARD-1 contains an C3HC4-type RING-HC finger that binds BRCA1 at its N-terminus and three tandem ankyrin repeats and tandem BRCT repeat domains at its C-terminus. The BRCT repeats bind CstF-50 (cleavage stimulation factor) to modulate mRNA processing and RNAP II stability in response to DNA damage.
Comment:C3HC4-type RING-HC finger consensus motif: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C, where X is any amino acid and the number of X residues varies in different fingers
Comment:A RING finger typically binds two zinc atoms, with its Cys and/or His side chains in a unique "cross-brace" arrangement.
Jiyao W et al.(2023). "The conserved domain database in 2023.",