{PDOC00180}
{PS00203; METALLOTHIONEIN_VRT}
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* Vertebrate metallothioneins signature *
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Metallothioneins (MT) [1,2,3] are small proteins  which bind heavy metals such
as zinc,  copper,  cadmium,  nickel, etc., through clusters of thiolate bonds.
MT's occur  throughout the animal kingdom and are also found in higher plants,
fungi and some prokaryotes. On the basis of structural relationships MT's have
been subdivided into three classes. Class I includes mammalian MT's as well as
MT's from crustacean and molluscs, but with clearly related primary structure.
Class II groups together MT's from various species such as sea urchins, fungi,
insects and   cyanobacteria   which   display   none   or  only  very  distant
correspondence to  class  I  MT's.  Class  III  MT's are atypical polypeptides
containing gamma-glutamylcysteinyl units.

Vertebrate class  I  MT's  are proteins of 60 to 68 amino acid residues, 20 of
these residues  are  cysteines  that  bind  to  7  bivalent  metal  ions. As a
signature pattern  we chose a region that spans 19 residues and which contains
seven of the metal-binding cysteines, this region is located in the N-terminal
section of class-I MT's.

-Consensus pattern: C-x-C-[GSTAP]-x(2)-C-x-C-x(2)-C-x-C-x(2)-C-x-K
                    [The 7 C's are involved in metal binding]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Note: This signature pattern is not meant to detect invertebrate class-I MT's
 whose sequence is highly divergent from that of vertebrate's.

-Expert(s) to contact by email:
           Binz P.-A.; binz@dim.hcuge.ch

-Last update: May 2004 / Text revised.

[ 1] Hamer D.H.
     "Metallothionein."
     Annu. Rev. Biochem. 55:913-951(1986).
     PubMed=3527054; DOI=10.1146/annurev.bi.55.070186.004405
[ 2] Kagi J.H.R., Schaffer A.
     "Biochemistry of metallothionein."
     Biochemistry 27:8509-8515(1988).
     PubMed=3064814
[ 3] Binz P.-A.
     Thesis, 1996, University of Zurich.

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