C2HC

C2HC refers to a class of zinc finger motifs in proteins characterized by the presence of two cysteine residues, one histidine residue, and a final cysteine residue that coordinate a zinc ion (commonly symbolized as Cys‑X2‑Cys‑Xn‑His‑X3‑Cys or similar spacing variations). As a subtype of zinc finger domains, C2HC motifs stabilize local protein structure through metal coordination and often contribute to interactions with nucleic acids, other proteins, or small molecules.

Structurally, C2HC motifs adopt compact folds that are stabilized by the tetrahedral coordination of a zinc ion. The precise spacing of the cysteine and histidine residues determines the fold geometry and functional properties. Compared with other zinc finger families (for example C2H2 or CCHC), C2HC motifs display distinct sequence patterns and structural features that tailor them to particular biochemical roles.

Functionally, proteins containing C2HC motifs participate in diverse cellular processes including transcriptional regulation, RNA binding, and assembly of multiprotein complexes. They occur across eukaryotes and in some viral proteins; specific biological activities depend on the surrounding protein context and additional domains. Mutations that disrupt zinc coordination can destabilize the motif and impair protein function, with potential implications for disease when such proteins play critical regulatory roles.

Because C2HC denotes a motif rather than a single protein, research continues to refine its structural classifications, sequence signatures, and functional annotations across different protein families.