RING finger, HC subclass, found in yeast Bre1 and its homologs from eukaryotes
Bre1 is an E3 ubiquitin-protein ligase that catalyzes monoubiquitination of histone H2B in concert with the E2 ubiquitin-conjugating enzyme, Rad6. The Rad6-Bre1-mediated histone H2B ubiquitylation modulates the formation of double-strand breaks (DSBs) during meiosis in yeast. it is also required, indirectly, for the methylation of histone 3 on lysine 4 (H3K4) and 79. RNF20, also known as BRE1A and RNF40, also known as BRE1B, are the mammalian homologs of Bre1. They work together to form a heterodimeric Bre1 complex that facilitate the K120 monoubiquitination of histone H2B (H2Bub1), a DNA damage-induced histone modification that is crucial for recruitment of the chromatin remodeler SNF2h to DNA double-strand break (DSB) damage sites. Moreover, the Bre1 complex acts as a tumor suppressor, augmenting expression of select tumor suppressor genes and suppressing select oncogenes. Deficiency in the mammalian histone H2B ubiquitin ligase Bre1 leads to replication stress and chromosomal instability. All subfamily members contain a C3HC4-type RING-HC finger at its C-terminus.
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.
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