The C3HC4 type zinc-finger (RING finger) is a cysteine-rich domain of 40 to 60 residues that coordinates two zinc ions, and has the consensus sequence: 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 [1]. Many proteins containing a RING finger play a key role in the ubiquitination pathway [2].

1: The RING finger domain: a recent example of a sequence-structure family. Borden KL, Freemont PS; Curr Opin Struct Biol 1996;6:395-401. PMID:8804826

2: RING fingers mediate ubiquitin-conjugating enzyme (E2)-dependent ubiquitination. Lorick KL, Jensen JP, Fang S, Ong AM, Hatakeyama S, Weissman AM; Proc Natl Acad Sci U S A 1999;96:11364-11369. PMID:10500182