{PDOC00244}
{PS00271; THIONIN}
{BEGIN}
****************************
* Plant thionins signature *
****************************

Thionins are small, basic, plant proteins generally toxic to animal cells [1].
They seem to exert  their  toxic effect  at the level of the cell membrane but
their exact  function  is  not  known. They consist of a polypeptide chain  of
forty five  to  fifty amino acids with three to four internal disulfide bonds.
They are found in seeds but also in the cell wall of leaves [2]. Thionins  are
processed from larger precursor proteins [3]. Crambin [4], a hydrophobic plant
seed protein,  also belongs to this family. The pattern we developed to detect
this family  of  proteins includes three of the six cysteine residues involved
in disulfide bonds.

          +-----------------------------------+
          |+----------------------------+     |
          ||                            |     |
        xxCCxxxxxxxxxxxCxxxxxxxxxCxxxCxxCxxxxxCxxxxxxxx
          **************         |
                       |         |
                       +---------+

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

-Consensus pattern: C-C-x(5)-R-x(2)-[FY]-x(2)-C
                    [The 3 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: The proteins from the gamma-thionin family are not related to the above
 proteins and are described in a separate section.

-Last update: May 2004 / Text revised.

[ 1] Vernon L.P., Evett G.E., Zeikus R.D., Gray W.R.
     "A toxic thionin from Pyrularia pubera: purification, properties, and
     amino acid sequence."
     Arch. Biochem. Biophys. 238:18-29(1985).
     PubMed=3985614
[ 2] Bohlmann H., Clausen S., Behnke S., Giese H., Hiller C.,
     Reimann-Phillip U., Schrader G., Barkholt V., Apel K.
     EMBO J. 7:1559-1565(1988).
[ 3] Bohlmann H., Apel K.
     Mol. Gen. Genet. 207:446-454(1987).
[ 4] Teeter M.M., Mazer J.A., L'Italien J.J.
     "Primary structure of the hydrophobic plant protein crambin."
     Biochemistry 20:5437-5443(1981).
     PubMed=6895315

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