The RING (Really Interesting New Gene) finger domain co-ordinates two Zn
2+ ions via conserved Cys and His residues. Most proteins which contain a RING finger are assumed to be ubiquitin (E3) ligases. The RING finger binds ubiquitin-conjugating enzymes (E2) and promotes direct transfer of ubiquitin to the target protein. (Adapted from
FBrf0215242 and
PMID:19489725).