RING finger, HC subclass, found in RNA polymerase II transcription factor B subunit 3 (TFB3) from fungi
TFB3, also known as RNA polymerase II transcription factor B 38 kDa subunit, RNA polymerase II transcription factor B p38 subunit, or Rig2, is a component of the general transcription and DNA repair factor IIH (TFIIH or factor B), which is essential for both basal and activated transcription and is involved in nucleotide excision repair (NER) of damaged DNA. TFIIH has CTD kinase and DNA-dependent ATPase activities, and is essential for polymerase II transcription in vitro. TFB3 is a homolog of MAT1 of higher eukaryotes which forms a ternary complex with MO15 (cdk7) and cyclin H. It physically interacts with Ubc4 and the Nedd8-conjugating enzyme Ubc12 as well as the Hrt1/Rtt101 complex. It targets the yeast Cul4-type cullin Rtt101 for its neddylation and ubiquitylation, and regulates neddylation and activity of cullin-3, but not Cdc53. TFB3 contains an N-terminal C3HC4-type RING-HC finger and a C-terminal MAT1 domain responsible for the interaction with the transcription factor TFIIH.
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.",