Modified RING finger, HC subclass (C4C4-type), found in CCR4-NOT transcription complex subunit 4 (NOT4) and similar proteins
NOT4, also known as CCR4-associated factor 4, E3 ubiquitin-protein ligase CNOT4, or potential transcriptional repressor NOT4, is a component of the multifunctional CCR4-NOT complex, a global regulator of RNA polymerase II transcription. It associates with polysomes and contributes to the negative regulation of protein synthesis. NOT4 functions as an E3 ubiquitin-protein ligase that interacts with a specific E2, Ubc4/5 in yeast, and the ortholog UbcH5B in humans, and ubiquitylates a wide range of substrates, including ribosome-associated factors. Thus, it plays a role in cotranslational quality control (QC) through ribosome-associated ubiquitination and degradation of aberrant peptides. NOT4 contains a C4C4-type RING finger motif, whose overall folding is similar to that of the C3HC4-type RING-HC finger, a central RNA recognition motif (RRM), and a C-terminal domain predicted to be unstructured.
Comment:consensus of the typical C3HC4-type RING-HC finger: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C, 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.",