{PDOC00875}
{PS01138; SCORP_SHORT_TOXIN}
{BEGIN}
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* Scorpion short toxins signature *
***********************************

Scorpion venoms  contain  a variety  of peptides toxic to mammals, insects and
crustaceans. Among these peptides there  is a family of short toxins (30 to 40
residues) [1,2] that currently consist of:

 - Inhibitors of calcium-activated and/or voltage-dependent potassium channels
   such as   charybdotoxin   (ChTX),  iberiotoxin  (IbTX),  kaliotoxin  (KTX),
   leiurotoxin I (LeTX I), margatoxin (MgTX) or noxiustoxin (NTX)
 - Inhibitors of chloride channels such as chlorotoxin.
 - Insect toxins such as insectotoxin I1, insectotoxin I5a and neurotoxin P2.

As shown  in  the following schematic representation, these toxins contain six
conserved cysteines   involved  in  disulfide  bonds.  Our  signature  pattern
contains the last five cysteines.

                             +---------------------+
                             |                     |
                             |     ************************
                      xxxxxxxCxxxxxCxxxCxxxxxxxxxxxCxxxxCxCxxx
                                   |   |                | |
                                   |   +----------------|-+
                                   +--------------------+

'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.

-Consensus pattern: C-x(3)-C-x(6,9)-[GAS]-K-C-[IMQT]-x(3)-C-x-C
                    [The 5 C's are involved in disulfide bonds]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Note: K+  channel  inhibitors have a lysine before the second cysteine in the
 patterns, while the other toxins have a glutamine.

-Last update: May 2004 / Text revised.

[ 1] Martin B.M., Ramirez A.N., Gurrola G.B., Nobile M., Prestipino G.,
     Possani L.D.
     "Novel K(+)-channel-blocking toxins from the venom of the scorpion
     Centruroides limpidus limpidus Karsch."
     Biochem. J. 304:51-56(1994).
     PubMed=7998956
[ 2] Lippens G., Najib J., Wodak S.J., Tartar A.
     "NMR sequential assignments and solution structure of chlorotoxin, a
     small scorpion toxin that blocks chloride channels."
     Biochemistry 34:13-21(1995).
     PubMed=7819188

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