|PROSITE documentation PDOC00449|
A number of eukaryotic and viral proteins contain a conserved cysteine-rich domain of 40 to 60 residues (called C3HC4 zinc-finger or 'RING' finger)  that binds two atoms of zinc. There are two different variants, the C3HC4-type and the C3H2C3-type, which is clearly related despite the different cysteine/histidine pattern. The latter type is sometimes referred to as "RING-H2 finger".
The 3D structure  of the zinc ligation system is referred to as the "cross-brace" motif. This atypical conformation is also shared by the FYVE (see <PDOC50178>) and PHD (see <PDOC50016>) domains. The way the "cross-brace" motif is binding two atoms of zinc is illustrated in the following schematic representation:
x x x x x x x x x x x x x x x x x C C C C x \ / x x \ / x x Zn x x Zn x C / \ C H / \ C x x x x x x x x x x x x x x x x x
'C': conserved cysteine involved zinc binding. 'H': conserved histidine involved in zinc binding. 'Zn': zinc atom.
Many proteins containing a RING finger play a key role in the ubiquitination pathway. The ubiquitination pathway generally involves three types of enzyme, know as E1, E2 and E3. E1 and E2 are ubiquitin conjugating enzymes. E1 acts first and passes ubiquitin to E2. E3 are ubiquitin protein ligases, responsible for substrate recognition. It has been shown [3,4] that several RING fingers act as E3 enzymes in the ubiquitination process.
Some proteins known to include a RING finger are listed below:
We developed a pattern that specifically recognized the C3HC4-type. We also developed a profile for C3HC4-type and RING-H2 type.Last update:
December 2001 / Text revised; profile added.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Borden K.L.B. Freemont P.S.|
|Title||The RING finger domain: a recent example of a sequence-structure family.|
|Source||Curr. Opin. Struct. Biol. 6:395-401(1996).|
|2||Authors||Borden K.L. Boddy M.N. Lally J. O'Reilly N.J. Martin S. Howe K. Solomon E. Freemont P.S.|
|Title||The solution structure of the RING finger domain from the acute promyelocytic leukaemia proto-oncoprotein PML.|
|Source||EMBO J. 14:1532-1541(1995).|
|3||Authors||Lorick K.L. Jensen J.P. Fang S. Ong A.M. Hatakeyama S. Weissman A.M.|
|Title||RING fingers mediate ubiquitin-conjugating enzyme (E2)-dependent ubiquitination.|
|Source||Proc. Natl. Acad. Sci. U.S.A. 96:11364-11369(1999).|
|4||Authors||Yokouchi M. Kondo T. Houghton A. Bartkiewicz M. Horne W.C. Zhang H. Yoshimura A. Baron R.|
|Title||Ligand-induced ubiquitination of the epidermal growth factor receptor involves the interaction of the c-Cbl RING finger and UbcH7.|
|Source||J. Biol. Chem. 274:31707-31712(1999).|