{PDOC51292}
{PS51292; ZF_RING_CH}
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* Zinc finger RING-CH-type profile *
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The RING finger is a well characterized zinc finger which coordinates two zinc
atoms  in a cross-braced manner (see <PDOC00449>). According to the pattern of
cysteines  and  histidines  three  different subfamilies of RING finger can be
defined.  The  classical  RING  finger (RING-HC) has a histidine at the fourth
coordinating  position  and  a  cysteine at the fifth. In the RING-H2 variant,
both  the  fourth and fifth positions are occupied by histidines. The RING-CH,
which is very similar to the classical RING finger, differs from both of these
variants  in that it has a cys residue in the fourth position and a His in the
fifth.  Another difference between the RING-CH and the common RING variants is
a   somewhat   longer   peptide   segment   between   the   fourth  and  fifth
zinc-coordinating  residues.  The  RING-CH  zinc  finger  has  thus  the  same
arrangement  of  cysteine  and  histidine  (C4HC3) as the PHD zinc finger (see
<PDOC50016>)  but  it contains features (spacing between the cysteines and the
histidine)  characteristic  of  the  genuine  RING-finger  (C3HC4)  [1,2]. The
RING-CH-type  is an E3 ligase mainly found in proteins associated to membranes
[3,4].

The solution structure of the RING-CH-type zinc finger of the herpesvirus Mir1
protein  has shown that it is an outlying relative of the cellular RING finger
domain family, with its polypeptide backbone much more closely resembling that
of  RING  domains  than  PHD  domains  (see  <PDB:1VYX>)  [5].  The  only real
difference  between  the  classic  and  variant  RING  domains, other than the
alteration  of zinc ligands, is the loss of the small beta-sheet found in RING
domains  and the replacement of one strand of this sheet with a single turn of
helix.

Some proteins that contains a RING-CH-type zinc finger are listed below:

 - Yeast  Doa10/SSM4.  An  E3  ligase  essential for the endoplasmic reticulum
   associated  degradation  (ERAD), an ubiquitin-proteasome system responsible
   for  the  degradation  of  membrane and lumenal proteins of the endoplasmic
   reticulum.
 - Mammalian membrane-associated RING-CH 1 to 9 (MARCH1 to 9) proteins.
 - Herpesvirus  modulator  of  immune  recognition  1. An E3 ubiquitin-protein
   ligase  which  promotes  ubiquitination  and subsequent degradation of host
   MHC-I  and CD1D molecules, presumably to prevent lysis of infected cells by
   cytotoxic T-lymphocytes.

The profile we developed covers the entire RING-CH-type zinc finger.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: February 2007 / First entry.

-Note:  The  RING-CH zinc finger profile is in competition with a profile of a
 related domain, i.e. RING-type zinc finger (see <PDOC500499>).

[ 1] Swanson R., Locher M., Hochstrasser M.
     "A conserved ubiquitin ligase of the nuclear envelope/endoplasmic
     reticulum that functions in both ER-associated and Matalpha2 repressor
     degradation."
     Genes Dev. 15:2660-2674(2001).
     PubMed=11641273; DOI=10.1101/gad.933301
[ 2] Aravind L., Iyer L.M., Koonin E.V.
     "Scores of RINGS but no PHDs in ubiquitin signaling."
     Cell Cycle 2:123-126(2003).
     PubMed=12695663
[ 3] Ismail N., Ng D.T.
     "Have you HRD? Understanding ERAD is DOAble!"
     Cell 126:237-239(2006).
     PubMed=16873052; DOI=10.1016/j.cell.2006.07.001
[ 4] Deng M., Hochstrasser M.
     "Spatially regulated ubiquitin ligation by an ER/nuclear membrane
     ligase."
     Nature 443:827-831(2006).
     PubMed=17051211; DOI=10.1038/nature05170
[ 5] Dodd R.B., Allen M.D., Brown S.E., Sanderson C.M., Duncan L.M.,
     Lehner P.J., Bycroft M., Read R.J.
     "Solution structure of the Kaposi's sarcoma-associated herpesvirus K3
     N-terminal domain reveals a Novel E2-binding C4HC3-type RING domain."
     J. Biol. Chem. 279:53840-53847(2004).
     PubMed=15465811; DOI=10.1074/jbc.M409662200

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