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PR00872

Identifier
MTDIPTERA  [View Relations]  [View Alignment]  
Accession
PR00872
No. of Motifs
3
Creation Date
26-JUN-1998  (UPDATE 21-JUN-1999)
Title
Diptera (Drosophila) metallothionein signature
Database References

PFAM; PF00131 metalthio
INTERPRO; IPR000966
PROTOMAP; P04357
FLYBASE; FBGN0002868; FBGN0012845
Literature References
1. KAGI, J.H.R.
Overview of Metallothioneins.
METHODS ENZYMOL. 205 613-626 (1991).
 
2. KAGI, J.H.R. AND KOJIMA, Y.
Chemistry and biochemistry of metallothionein.
EXPERIENTIA SUPPL. 52 25-61 (1987).
 
3. KAGI, J.H.R. AND SCHAFFER, A.
Biochemistry of metallothionein.
BIOCHEMISTRY 27 8509-8515 (1988).
 
4. FOWLER, B.A., HILDEBRAND, C.E., KOJIMA, Y. AND WEBB, M.
Nomenclature of metallothionein.
EXPERIENTIA SUPPL. 52 21 (1987).
 
5. KOJIMA, Y.
Definitions and nomenclature of metallothioneins.
METHODS ENZYMOL. 205 8-10 (1991).
 
6. BINZ, P.-A. AND KAGI, J.H.R.
Molecular evolution of the metallothionein. Suggestions for a natural 
classification system.
FOURTH INTERNATIONAL MEETING ON METALLOTHIONEIN, KANSAS CITY (USA), 1997.
 
7. LASTOWSKI-PERRY D., OTTO E. AND MARONI G.
Nucleotide sequence and expression of a Drosophila metallothionein. 
J.BIOL.CHEM. 260 1527-1530 (1985). 

Documentation
Metallothioneins (MT) are small proteins that bind heavy metals, such as
zinc, copper, cadmium, nickel, etc.. They have a high content of cysteine
residues that bind the metal ions through clusters of thiolate bonds [1-3]
(http://www.unizh.ch/~mtpage/MT.html). An empirical classification into
three classes has been proposed by Fowler et al. [4] and Kojima [5]. Members
of class I are defined to include polypeptides related in the positions of
their cysteines to equine MT-1B, and include mammalian MTs as well as MTs 
from crustaceans and molluscs. Class II groups MTs from a variety of 
species, including sea urchins, fungi, insects and cyanobacteria. Class
III MTs are atypical polypeptides composed of gamma-glutamylcysteinyl
units [4]. 
 
This original classification system has been found to be limited, in the
sense that it does not allow clear differentiation of patterns of structural
similarities, either between or within classes. Consequently, all class I
and class II MTs (the proteinaceous sequences) have now been grouped into
families of phylogenetically-related and thus alignable sequences [6]
(http://www.unizh.ch/~mtpage/classif.html). This system subdivides the MT
superfamily into families, subfamilies, subgroups, and isolated isoforms
and alleles. 
 
The metallothionein superfamily comprises all polypeptides that resemble
equine renal metallothionein in several respects [4]: e.g., low molecular
weight; high metal content; amino acid composition with high Cys and low
aromatic residue content; unique sequence with characteristic distribution
of cysteines, and spectroscopic manifestations indicative of metal thiolate
clusters. A MT family subsumes MTs that share particular sequence-specific 
features and are thought to be evolutionarily related. The inclusion of a
MT within a family presupposes that its amino acid sequence is alignable 
with that of all members. Fifteen MT families have been characterised, each
family being identified by its number and its taxonomic range: e.g., Family
1: vertebrate MTs.
 
Diptera (Drosophila, family 5) MTs are 40-43 residue proteins that contain
10 conserved cysteines arranged in five Cys-X-Cys groups. In particular, the
consensus pattern C-G-x(2)-C-x-C-x(2)-Q-x(5)-C-x-C-x(2)-D-C-x-C has been 
found to be diagnostic of family 5 MTs. The protein is found primarily in
the alimentary canal, and its induction is stimulated by ingestion of
cadmium or copper [7]. Mercury, silver and zinc induce the protein to a 
lesser extent.
 
MTDIPTERA is a 3-element fingerprint that provides a signature for diptera 
(Drosophila, family 5) metallothioneins. The fingerprint was derived from 
an initial alignment of 3 sequences: motif 1 contains 4 metal-binding 
Cys residues; and motifs 2 and 3 each encode 3 cysteines, and span the 
characteristic consensus pattern, which contains 3 of the 5 Cys-x-Cys 
groups. A single iteration on OWL30.1 was required to reach convergence, 
no further sequences being identified beyond the starting set.
 
An update on SPTR37_9f identified a true set of 3 sequences.
Summary Information
3 codes involving  3 elements
0 codes involving 2 elements
Composite Feature Index
3333
2000
123
True Positives
MT1_DROME     MT1_DROSI     MT2_DROME     
Sequence Titles
MT1_DROME   METALLOTHIONEIN 1 (MT-1) - DROSOPHILA MELANOGASTER (FRUIT FLY). 
MT1_DROSI METALLOTHIONEIN 1 (MT-1) - DROSOPHILA SIMULANS (FRUIT FLY), AND DROSOPHILA ANANASSAE (FRUIT FLY).
MT2_DROME METALLOTHIONEIN 2 (MT-2) - DROSOPHILA MELANOGASTER (FRUIT FLY).
Scan History
OWL30_1    1  300  NSINGLE    
SPTR37_9f 1 25 NSINGLE
Initial Motifs
Motif 1  width=13
Element Seqn Id St Int Rpt
CPCGSGCKCASQA MT1_DROME 3 3 -
CPCGSGCKCASQA MT1_DROSI 3 3 -
KGCGTNCQCSAQK MT2_DROME 4 4 -

Motif 2 width=13
Element Seqn Id St Int Rpt
ATKGSCNCGSDCK MT1_DROME 15 -1 -
ATKGSCNCGSDCK MT1_DROSI 15 -1 -
KCGDNCACNKDCQ MT2_DROME 16 -1 -

Motif 3 width=14
Element Seqn Id St Int Rpt
KCGGDKKSACGCSE MT1_DROME 27 -1 -
KCGGDKKSACGCSK MT1_DROSI 27 -1 -
QCVCKNGPKDQCCS MT2_DROME 28 -1 -
Final Motifs
Motif 1  width=13
Element Seqn Id St Int Rpt
CPCGSGCKCASQA MT1_DROME 3 3 -
CPCGSGCKCASQA MT1_DROSI 3 3 -
KGCGTNCQCSAQK MT2_DROME 4 4 -

Motif 2 width=13
Element Seqn Id St Int Rpt
ATKGSCNCGSDCK MT1_DROME 15 -1 -
ATKGSCNCGSDCK MT1_DROSI 15 -1 -
KCGDNCACNKDCQ MT2_DROME 16 -1 -

Motif 3 width=14
Element Seqn Id St Int Rpt
KCGGDKKSACGCSE MT1_DROME 27 -1 -
KCGGDKKSACGCSK MT1_DROSI 27 -1 -
QCVCKNGPKDQCCS MT2_DROME 28 -1 -