{PDOC51266}
{PS51266; ZF_CHY}
{PS51270; ZF_CTCHY}
{BEGIN}
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* Zinc finger CHY-type and CTCHY-type profiles *
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Pirh2  is  an  eukaryotic  ubiquitin  protein  ligase, which has been shown to
promote  p53  degradation  in mammals. Pirh2 physically interacts with p53 and
promotes  ubiquitination  of  p53  independently  of MDM2. Like MDM2, Pirh2 is
thought  to  participate  in an autoregulatory feedback loop that controls p53
function.  Pirh2  proteins  contain three distinct zinc fingers, the CHY-type,
the  CTCHY-type  which  is  C-terminal  to the CHY-type zinc finger and a RING
finger  (see <PDOC00449>). The CHY-type zinc finger has no known functions but
the  region encompassing the CTCHY-type zinc finger is required for binding to
p53 in mammals [1].

The  CTCHY-type  zinc  finger  is  only  found  in pirh2 proteins, whereas the
CHY-type zinc finger is also found in the following proteins:

 - Yeast  helper  of Tim protein 13. Hot13 may have a role in the assembly and
   recycling  of  the small Tims, a complex of the mitochondrial intermembrane
   space  that  participates  in  the TIM22 import pathway for assembly of the
   inner membrane [2].
 - Several  plant  hypothetical  proteins that also contain hemerythrin cation
   binding domains.
 - Several protozoan hypothetical proteins that also contain a Myb domain.

The  solution  structure  of  the CHY-type and the CTCHY-type zinc fingers has
been  solved  (see  <PDB:2DKT>).  Each  conserved region binds 3 zinc atoms as
shown in the following schematic representations:

The CHY-type zinc finger:

                      ++---------+-----+
                      ||         |     |
         CXHYxxxxxxxxxCCxxxxxCxxCHxxxxxHxxxxxxxxxxxCxxCxxxxxxxxxCxxC
         | |                 |  |                  |  |         |  |
         +-+-----------------+--+                  +--+---------+--+

The CTCHY-type zinc finger:

                             +--+------------+------+
                             |  |            |      |
              CxxCxxxxxxxxxxHCxxCxxCxxxxxxxxxHCxxCxxCxxxxxxxxHxC
              |  |          |      |          |  |           | |
              +--+----------+------+          +--+-----------+-+

'C': conserved cysteine involved in the binding of one zinc atom.
'H': conserved histidine involved in the binding of one zinc atom.

The  first  profile  covers the entire CHY-type zinc finger and the second one
the whole CTCHY-type zinc finger.

-Sequences known to belong to this class detected by the first profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Sequences known to belong to this class detected by the second profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: November 2006 / First entry.

[ 1] Leng R.P., Lin Y., Ma W., Wu H., Lemmers B., Chung S., Parant J.M.,
     Lozano G., Hakem R., Benchimol S.
     "Pirh2, a p53-induced ubiquitin-protein ligase, promotes p53
     degradation."
     Cell 112:779-791(2003).
     PubMed=12654245
[ 2] Curran S.P., Leuenberger D., Leverich E.P., Hwang D.K., Beverly K.N.,
     Koehler C.M.
     "The role of Hot13p and redox chemistry in the mitochondrial TIM22
     import pathway."
     J. Biol. Chem. 279:43744-43751(2004).
     PubMed=15294910; DOI=10.1074/jbc.M404878200

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