RING finger, HC subclass, found in RING finger protein MAT1
MAT1, also known as CDK-activating kinase assembly factor MAT1, CDK7/cyclin-H assembly factor, cyclin-G1-interacting protein, menage a trois, RING finger protein 66 (RNF66), p35, or p36, is involved in cell cycle control and in RNA transcription by RNA polymerase II. It associates primarily with the catalytic subunit cyclin-dependent kinase 7 (CDK7) and the regulatory subunit cyclin H to form the CDK-activating kinase (CAK) complex that can further associate with the core-TFIIH to form the transcription factor IIH (TFIIH) basal transcription/DNA repair factor, which activates RNA polymerase II by serine phosphorylation of the repetitive C-terminal domain (CTD) of its large subunit (POLR2A), allowing its escape from the promoter, and elongation of the transcripts. MAT1 contains an N-terminal C3HC4-type RING-HC finger, a central coiled coil domain, and a C-terminal domain rich in hydrophobic residues.
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.",