metallo.txt
----------------------------------------------------------------------------
UniProt - Swiss-Prot Protein Knowledgebase
Swiss Institute of Bioinformatics (SIB); Geneva, Switzerland
European Bioinformatics Institute (EBI); Hinxton, United Kingdom
Protein Information Resource (PIR); Washington DC, USA
----------------------------------------------------------------------------
Description: Metallothioneins: classification and list of entries
Name: metallo.txt
Release: 55.5 of 10-Jun-2008
----------------------------------------------------------------------------
This document provides both a brief description of the classification of
metallothioneins into families as developed by Pierre-Alain Binz and Jeremias
H.R. Kagi as well as the list, classified by family, of the metallothionein
entries in UniProtKB/Swiss-Prot. The definition of the metallothionein
superfamily and its subdivisions is presented at the bottom of this file. The
description of the criteria characterising all families and subfamilies is
to be found at:
http://www.bioc.unizh.ch/mtpage/MT.html
Comments about the metallothionein families classification should be sent to:
Pierre-Alain Binz
Swiss Institute of Bioinformatics
CMU
1, Rue Michel Servet
1211 Geneva 4
Switzerland
E-mail: pierre-alain.binz@isb-sib.ch
========================
Metallothionein families
========================
Introduction
------------
Metallothioneins (MTs) constitute a superfamily of low molecular weight
cysteine-rich metalloproteins and metallopeptides responsible for regulating
the intracellular supply of the biologically essential zinc and copper ions
and for protecting cells from the deleterious effects of exposure to elevated
amounts of these and non-essential polarizable transition and posttransition
metal ions such as Cd2+, Hg2+ and others. Since its discovery as a cadmium and
zinc containing protein in horse kidney by Margoshes and Vallee [1] MT has
been an object of intensive study in various branches of the life sciences
[2,3]. MT is now known to occur in all animal phyla examined so far as well as
in certain fungi, plants and cyanobacteria.
In mammals, 20 totally conserved cysteine residues (Cys) bind, in the reduced
form, a complement of 7 equivalents of polarizable bivalent metal ions giving
rise to two unique metal-thiolate clusters with characteristic spectroscopic
features [4]. The spontaneous refolding of the native structure upon metal
addition attests to a guiding role of the positions of the Cys and other AAs
conserved in the polypeptide chain. The invertebrate holo-MTs studied thusfar
display similar clusters with structural and compositional variations due to
different numbers and relative positions of the Cys residues on the
polypeptide chain.
An empirical classification into three classes was proposed by Fowler et al.
[5] and Kojima [6]. Members of Class I are defined to include polypeptides
related in the positions of the Cys to equine MT-1B while those of class II
display none or very distant correspondence in this respect. Class I subsumes
besides the vertebrate MTs all presently known crustacean and molluscan
sequences. Class III MTs are polyisopeptides composed of atypical gamma-
glutamylcysteinyl units and are no therefore direct gene products [5]. Since
this classification system does not allow to differentiate clearly patterns
of structural similarities we have now grouped all proteinaceous MT sequences
(Class I and Class II) into families of phylogenetically related and,
accordingly, alignable sequences. The subclassification discriminating
subfamilies and subgroups of MT sequences is based on phylogenetic analyses
inferred from both amino-acid and polynucleotide sequences [7-9].
The web page containing all details of the classification system, including
strategy and results is to be found at:
http://www.bioc.uzh.ch/mtpage/MT.html
References
----------
[1] Margoshes M., Vallee B.L.
A cadmium protein from equine kidney cortex.
J. Am. Chem. Soc. 79:4813-4814(1957).
[2] Kagi J.H.R.
Overview of Metallothioneins.
Methods Enzymol. 205:613-626(1991).
[3] Kagi J.H.R., Kojima Y.
Chemistry and biochemistry of metallothionein.
Experientia Suppl. 52:25-61(1987).
[4] Kagi J.H.R., Schaffer A.
Biochemistry of metallothionein.
Biochemistry 27:8509-8515(1988).
[5] Fowler B.A., Hildebrand C.E., Kojima Y., Webb M.
Nomenclature of metallothionein.
Experientia Suppl. 52:21(1987).
[6] Kojima Y.
Definitions and nomenclature of metallothioneins.
Methods Enzymol. 205:8-10(1991).
[7] Binz P.-A.
Metallothioneins: studies on molecular evolution and on the structural
and chiroptical features of their metal thiolate clusters.
PhD thesis, University Zurich, Switzerland (1996).
[8] Kojima Y., Binz P.-A., Kagi J.H.R.
Nomenclature of metallothionein: proposal for a revision.
(In) Metallothionein IV, Klaassen C. (Ed.), pp3-6, Birkhauser Verlag,
Basel, (1999).
[9] Binz P.-A., Kagi J.H.R.
Metallothionein: molecular evolution and classification.
(In) Metallothionein IV, Klaassen C. (Ed.), pp7-13, Birkhauser Verlag,
Basel, (1999).
------------------------------------------------------------------------------
=============================================
Swiss-Prot entries for metallothioneins (MTs)
=============================================
Notes:
Subdiv. = subdivision
Subdivisions are described for each family
Rem. = remarks:
v: variant(s) known
c: conflict(s) known
p: partial sequence
Source = molecular source:
AA: protein sequence
NA: nucleic acid sequence
The criteria used for the classifications are described at the bottom of this
document.
========================
Family 1: vertebrate MTs
========================
Pattern: K-x(1,2)-C-C-x-C-C-P-x(2)-C
3D structure status: available for mouse Cd7-MT-1 (PDB: 1dfs, 1dft)
human Cd7-MT-2 (PDB: 1hmu, 2hmu)
rabbit Cd7-MT-2 (PDB: 1mrb, 2mrb)
rat Cd7-MT-2 (PDB: 1mrt, 2mrt, 4mt2)
rat Cd5Zn2-MT-2 (Braun et al. 1992,
PNAS USA 89:10124-10128,
not in PDB)
Known taxonomic range: vertebrata
Multiple sequence alignment: yes
Phylogenetic trees: yes
Subdivisions: m1: mammalian MT-1
m2: mammalian MT-2
m3: mammalian MT-3
m4: mammalian MT-4
m : mammalian MT
a1: avian MT-1
a2: avian MT-2
a : avian MT
r : reptilian MT
t : teleost MT
s : sharks MT
b : batracian MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_BOVIN (P58280) M1 AA
MT1A_BOVIN (P67983) m1 c AA/NA
MT1H_BOVIN (P55942) m AA
MT2_BOVIN (P68301) m2 AA
MT2H_BOVIN (P55943) m AA
MT1_CANFA (O19000) m1 AA/NA
MT2_CANFA (Q9XST5) m2 AA/NA
MT1_CRIGR (P02804) m1 NA
MT2_CRIGR (P67981) m2 NA
MT2_CRILO (P68041) m2 NA
MT2_MESAU (P17808) m2 NA
MT1A_HORSE (P02800) m1 v AA
MT1B_HORSE (P02801) m2 AA
MT1_MOUSE (P02802) m1 c AA/NA
MT2_MOUSE (P02798) m2 c AA/NA
MT1A_PIG (P49068) m1 c NA
MT1C_PIG (P79376) m1 NA
MT1D_PIG (P79377) m1 NA
MT1E_PIG (P79431) m1 NA
MT1F_PIG (P79378) m1 NA
MT2A_PIG (P79379) m2 NA
MT2B_PIG (P79380) m2 NA
MT1A_RABIT (P11957) m1 AA/NA
MT2A_RABIT (P18055) m AA
MT2B_RABIT (P80289) m AA
MT2C_RABIT (P80290) m AA
MT2D_RABIT (P80291) m AA
MT2E_RABIT (P80292) m AA
MT1_RAT (P02803) m1 AA/NA
MT2_RAT (P04355) m2 AA/NA
MT1A_SHEEP (P67982) m1 c NA
MT1B_SHEEP (P09577) m1 NA
MT1C_SHEEP (P09578) m1 NA
MT2_SHEEP (P68302) m2 NA
MT2_STECO (P14425) m1 AA
MT1_CERAE (P02797) m1 NA
MT2_CERAE (P68304) m2 NA
MT1A_HUMAN (P04731) m1 NA
MT1B_HUMAN (P07438) m1 NA
MT1E_HUMAN (P04732) m1 AA/NA
MT1F_HUMAN (P04733) m1 AA/NA
MT1G_HUMAN (P13640) m1 AA/NA
MT1H_HUMAN (P80294) m1 AA/NA
MT1L_HUMAN (Q93083) m1 AA/NA
MT1M_HUMAN (Q8N339) m1 NA
MT1X_HUMAN (P80297) m1 AA/NA
MT2_HUMAN (P02795) m2 AA/NA
MT2_MACFA (P68303) m2 NA
MT2_PONAB (Q5NVS0) m2 NA
MT3_BOSMU (Q2MJS5) m3 NA
MT3_BOVIN (P37359) m3 AA
MT3_HORSE (P37360) m3 AA
MT3_HUMAN (P25713) m3 AA/NA
MT3_MACFA (Q2PFZ0) m3 NA
MT3_MOUSE (P28184) m3 NA
MT3_PIG (P55944) m3 NA
MT3_RABIT (Q2PS21) m3 NA
MT3_RAT (P37361) m3 NA
MT3_SHEEP (Q8MKE4) m3 NA
MT4_CANFA (Q9TUI5) m4 NA
MT4_HUMAN (P47944) m4 NA
MT4_MOUSE (P47945) m4 NA
MT_BALMY (O18842) m NA
MT_ANAPL (P68494) a1 AA/NA
MT_CAIMO (P68495) a1 AA/NA
MT_CHICK (P68497) a1 AA/NA
MT1_COLLI (P15786) a1 AA
MT2_COLLI (P15787) a2 AA
MTA_COLVI (P27086) a p NA
MTB_COLVI (P27087) a p NA
MT_MELGA (P68498) a1 NA
MT_PHACO (P68499) a1 p NA
MT_PODSI (Q708T3) r NA
MT1_DANRE (P52722) t NA
MT2_DANRE (Q7ZSY6) t NA
MT_CARAU (P52723) t c NA
MTA_CARCW (Q8AWG2) t NA
MTB_CARCW (Q8AWG1) t NA
MTA_CHAAC (O93593) t NA
MTB_CHAAC (P52724) t NA
MTA_CHIHA (P68506) t NA
MTB_CHIHA (P62711) t NA
MTA_CHIRA (P62338) t NA
MTB_CHIRA (P62679) t NA
MT1_CYPCA (O13269) t NA
MT2_CYPCA (Q9I9I0) t NA
MTA_CYPS1 (Q92044) t NA
MTB_DICLA (Q9PTG9) t NA
MT_ESOLU (P25127) t NA
MT_GADMO (P51902) t c NA
MT_GOBCO (Q800D3) t NA
MTA_GYMAC (P68507) t NA
MTB_GYMAC (P62713) t NA
MT_ICTPU (O93571) t NA
MT_LITMO (Q8UVY1) t NA
MT_LIZAU (O13257) t NA
MTB_MORSA (P62712) t NA
MT_NOEBA (P25128) t NA
MTA_NOTCO (P62339) t NA
MTB_NOTCO (P62680) t NA
MTA_ONCMY (P68503) t NA
MTB_ONCMY (P68501) t NA
MT_OREAU (Q7ZZP9) t NA
MT_OREMO (P52726) t c NA
MT_ORYLA (Q6S4N8) t NA
MTA_PAGBE (O93609) t NA
MTB_PAGBE (P62678) t NA
MTA_PAGBO (P68508) t NA
MTB_PAGBO (P62681) t NA
MT_PAGMA (Q9IB50) t NA
MTA_PARCR (O93450) t NA
MTB_PARCR (P62682) t NA
MT_PERFL (P52725) t NA
MT_PLEAT (Q6XUW5) t NA
MT_PLEPL (P07216) t AA/NA
MT_PSEAM (P55945) t AA/NA
MT_RUTRU (P80593) t AA
MTA_SALAL (P68505) t c NA
MTB_SALAL (P68502) t c NA
MTA_SALSA (P68504) t NA
MTB_SALSA (P52720) t NA
MTA_SPAAU (P52727) t NA
MTA_THECR (P52721) t NA
MT_ZOAVI (P52728) t NA
MT_SCYTO (Q6J1T3) s NA
MT_AMBME (O42152) b NA
MT_XENLA (Q05890) b NA
=====================
Family 2: mollusc MTs
=====================
Pattern: C-x-C-x(3)-C-T-G-x(3)-C-x-C-x(3)-C-x-C-K
3D structure status: not available
Known taxonomic range: pelecypoda, gastropoda
Multiple sequence alignment: yes
Phylogenetic trees: yes
Subdivisions: mo1: mussel MT-1
mo2: mussel MT-2
mog: gastropod MT
mo : other mollusc MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT_CRAVI (P23038) mo AA/NA
MT_DREPO (Q94550) mo NA
MT10A_MYTED (P80246) mo1 AA/NA
MT10B_MYTED (O62554) mo1 NA
MT12_MYTED (P80247) mo1 c AA/NA
MT13_MYTED (P80248) mo1 AA/NA
MT14_MYTED (P80249) mo1 AA/NA
MT21_MYTED (P80251) mo2 v AA
MT22_MYTED (P80252) mo2 AA/NA
MT23A_MYTED (P69153) mo2 AA
MT23B_MYTED (P80258) mo2 AA
MT23A_MYTGA (P69154) mo2 NA
MT_PERVI (Q9U568) mo c NA
MT_ARIAR (P55946) mog v AA
MTCD_HELPO (P33187) mog AA
MTCU_CALSI (Q9U620) mog NA
MTCU_HELPO (P55947) mog AA
========================
Family 3: crustacean MTs
========================
Pattern: P-[GD]-P-C-C-x(3,4)-C-x-C
3D structure status: available for blue crab Cd6-MT-I (PDB: 1dmc, 1dmd, 1dme)
for mud crab Cd6-MT1 (Not yet in PDB)
Known taxonomic range: crustacea
Multiple sequence alignment: yes
Phylogenetic trees: yes
Subdivisions: c : crustacean MT
c1: crustacean MT-1
c2: crustacean MT-2
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT_CARMA (P55948) c2 v AA
MT1_CALSI (P55949) c1 v AA
MT2_CALSI (P55950) c2 v AA
MT1_SCYSE (P02805) c1 AA
MT2_SCYSE (P02806) c2 AA
MT1_HOMAM (P29499) c AA
MT_ASTFL (P55951) c v AA
MT_POTPO (P55952) c AA
===========================
Family 4: echinodermata MTs
===========================
Pattern: P-D-x-K-C-V-C-C-x(5)-C-x-C-x(4)-C-C-x(4)-C-C-x(4,6)-C-C
3D structure status: available for sea urchin Cd7-MTA (1qjk, 1qjl)
Known taxonomic range: echinoidea
Multiple sequence alignment: yes
Phylogenetic trees: yes
Subdivisions: e1: echinodermata MT type 1
e2: echinodermata MT type 2
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT_LYTPI (O02033) e2 NA
MT_PARLI (P80367) e2 AA
MTA_STRPU (P04734) e1 c NA
MTB_STRPU (Q27287) e1 NA
MTA_SPHGR (Q26497) e2 p NA
MTB_SPHGR (Q26496) e2 p NA
MT_STENE (P55953) e1 NA
=====================
Family 5: diptera MTs
=====================
Pattern: C-G-x(2)-C-x-C-x(2)-Q-x(5)-C-x-C-x(2)-D-C-x-C
3D structure status: not available
Known taxonomic range:
Multiple sequence alignment: yes
Phylogenetic trees: no
Subdivisions: d1: diptera MT type 1
d2: diptera MT type 2
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_DROAN (P61873) d1 NA
MT1_DROME (P04357) d1 NA
MT1_DROSI (P61874) d1 NA
MT2_DROME (P11956) d2 NA
MT3_DROME (Q9VDN2) d2 NA
MT4_DROME (Q8I9B4) d2 NA
======================
Family 6: nematoda MTs
======================
Pattern: K-C-C-x(3)-C-C
3D structure status: not available
Known taxonomic range: secernentea
Multiple sequence alignment: yes
Phylogenetic trees: no
Subdivisions: n1: nematoda MT type 1
n2: nematoda MT type 2
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_CAEEL (P17511) n1 c NA
MT2_CAEEL (P17512) n2 NA
=====================
Family 7: ciliata MTs
=====================
Pattern: -
3D structure status: not available
Known taxonomic range: ciliata (protozoa)
Multiple sequence alignment: no
Phylogenetic trees: no
Subdivisions: ci: ciliata MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_TETPI (P80394) ci AA/NA
MT1_TETPY (O97388) ci AA/NA
MT1_TETTH (Q8T6B3) ci NA
MTCD_TETTH (Q8WSW3) ci NA
=====================
Family 8: fungi-I MTs
=====================
Pattern: C-G-C-S-x(4)-C-x-C-x(3,4)-C-x-C-S-x-C
3D structure status: available for N.crassa Cu6-MT (Not yet in PDB)
Known taxonomic range: basidiomycotina, deuteromycotina, ascomycotina
Multiple sequence alignment: yes
Phylogenetic trees: no
Subdivisions: f1: fungi-I MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT_AGABI (P04358) f1 AA
MT1_COLGL (Q99334) f1 NA
MT2_COLGL (Q00369) f1 NA
MT1_NECLU (P84865) f1 AA
MT_NEUCR (P02807) f1 c AA/NA
======================
Family 9: fungi-II MTs
======================
Pattern: -
3D structure status: not available
Known taxonomic range: deuteromycotina
Multiple sequence alignment: no
Phylogenetic trees: no
Subdivisions: f2: fungi-II MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_CANGA (P15113) f2 AA/NA
========================
Family 10: fungi-III MTs
========================
Pattern: -
3D structure status: not available
Known taxonomic range: deuteromycotina
Multiple sequence alignment: no
Phylogenetic trees: no
Subdivisions: f3
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT2_CANGA (P15114) f3 v AA/NA
=======================
Family 11: fungi-IV MTs
=======================
Pattern: C-X-K-C-x-C-x(2)-C-K-C
3D structure status: not available
Known taxonomic range: ascomycotina
Multiple sequence alignment: no
Phylogenetic trees: no
Subdivisions: f4: fungi-IV MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_YARLI (P41927) f4 NA
MT2_YARLI (P41928) f4 NA
MT3_YARLI (Q9HFD0) f4 NA
MT4_YARLI (Q9HFC9) f4 NA
======================
Family 12: fungi-V MTs
======================
Pattern: -
3D structure status: PDB: 1aoo, 1aqq, 1aqr, 1aqs
Known taxonomic range: ascomycotina
Multiple sequence alignment: yes
Phylogenetic trees: no
Subdivisions: f5: fungi-V MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MTCU_YEAST (P07215) f5 AA/NA
=======================
Family 13: fungi-VI MTs
=======================
Pattern: -
3D structure status: not available
Known taxonomic range: ascomycotina
Multiple sequence alignment: no
Phylogenetic trees: no
Subdivisions: f6: fungi-VI MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
CRS5_YEAST (P41902) f6 NA
=========================
Family 14: prokaryota MTs
=========================
Pattern: K-C-A-C-x(2)-C-L-C
3D structure status: not available
Known taxonomic range: cyanobacteria
Multiple sequence alignment: yes
Phylogenetic trees: no
Subdivisions: pr: prokaryota MT
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT_SYNP7 (P30331) pr AA/NA
MT_SYNSP (P08002) pr AA
MT_SYNVU (P30565) pr NA
====================
Family 15: plant MTs
====================
Pattern: [YFH]-x(5,25)-C-[SKD]-C-[GA]-[SDPAT]-x(0,1)-C-x-[CYF]
Note: yields all plant sequences, but also MTCU_HELPO (P55947) and the non-MT
ITB3_HUMAN (P05106)
3D structure status: not available
Known taxonomic range: angiospermae (magnolophyta)
Multiple sequence alignment: yes
Phylogenetic trees: yes
Subdivisions: p1 : plant MT type 1
p2 : plant MT type 2
p3 : plant MT type 3
p21: plant MT type 2x1
pec: plant EC MT-like protein
Swiss-Prot Subdiv. Rem. Source
Entry name AC
-------------------- ------- ---- ------
MT1_CASGL (Q39511) p1 NA
MT1_CICAR (Q39458) p1 NA
MT1_FESRU (O24528) p1 NA
MT1_HORVU (P26571) p1 NA
MT1_MAIZE (P30571) p1 NA
MT1A_ORYSI (A2ZH20) p1 NA
MT1A_ORYSJ (P0C5B3) p1 NA
MT1B_ORYSJ (Q10N03) p1 NA
MT1_PEA (P20830) p1 NA
MT1_TRIRP (P43399) p1 NA
MT1A_VICFA (Q41669) p1 NA
MT1B_VICFA (Q41670) p1 NA
MT1_WHEAT (P43400) p1 NA
MT2_ACTCH (P43390) p2 NA
MT2A_ARATH (P25860) p2 c NA
MT2B_ARATH (Q38805) p2 NA
MT21_BRAJU (P56168) p2 NA
MT22_BRAJU (P69163) p2 NA
MT23_BRAJU (P56170) p2 NA
MT25_BRAJU (P56172) p2 NA
MT2_BRANA (Q96353) p2 p NA
MT2_BRARA (P69164) p2 c NA
MT2_BRARP (Q39269) p2 NA
MT2_CICAR (Q39459) p2 p NA
MT1_COFAR (P43396) p2 NA
MT2_FRAAN (P93134) p2 NA
MT2_MALDO (O24058) p2 NA
MT2_MUSAC (O22319) p2 NA
MT2_NICGU (Q40396) p2 NA
MT2_NICPL (Q40410) p2 NA
MT2A_ORYSJ (P94029) p2 NA
MT2B_ORYSJ (Q5JM82) p2 NA
MT2C_ORYSI (A2XZL0) p2 NA
MT2C_ORYSJ (A3AZ88) p2 NA
MT2_RICCO (P30564) p2 NA
MT2A_SOLLC (Q40157) p2 NA
MT2B_SOLLC (Q40158) p2 c NA
MT2X_SOLLC (Q43512) p2 NA
MT2Y_SOLLC (Q43513) p2 NA
MT2Z_SOLLC (Q43515) p2 NA
MT2_TRIRP (P43398) p2 NA
MT2_VICFA (Q41657) p2 NA
MT1_MIMGU (P20238) p2 c NA
MT1A_ARATH (P43392) p21 NA
MT1B_ARATH (Q38803) p21 NA
MT1C_ARATH (Q38804) p21 NA
MT54_BRANA (P43402) p21 NA
MT3_ACTCH (P43389) p3 NA
MT3_CARPA (Q96386) p3 NA
MT3_MALDO (O24059) p3 NA
MT3_MUSAC (Q40256) p3 NA
MT3A_ORYSI (A2WLS0) p3 NA
MT3A_ORYSJ (A1YTM8) p3 NA
MT3B_ORYSI (A2Y1D7) p3 NA
MT3B_ORYSJ (A3B0Y1) p3 NA
MT3_PICGL (Q40854) p3 NA
MT3_PRUAV (O48951) p3 NA
MT4A_ORYSJ (Q0IMG5) p4 NA
MT4B_ORYSJ (Q2QNE8) p4 NA
MT4C_ORYSJ (Q2QNC3) p4 NA
EC1_ARATH (P93746) pec NA
EC2_ARATH (Q42377) pec NA
EC_MAIZE (P43401) pec NA
MT21A_ORYSJ (Q109B0) pec NA
EC1_WHEAT (P30569) pec c AA/NA
EC3_WHEAT (P30570) pec NA
==========================================================================
Family 99: phytochelatins and other non-proteinaceous MT-like polypeptides
==========================================================================
Note: gammaglutamyl-cysteinyl units, these are not proteins.
3D structure status: not available
Known taxonomic range: planta
Subdivisions: not defined
------------------------------------------------------------------------------
==================================================================
Definition of the metallothionein superfamily and its subdivisions
==================================================================
The metallothionein superfamily is defined phenomenologically as comprising
all polypeptides which resemble equine renal metallothionein in several of
their features (Nordberg & Kojima 1979, Fowler et al. 1987). Such general
features are low molecular weight, high metal content, characteristic amino
acid composition (high Cys content, low content of aromatic amino acid
residues), unique amino acid sequence with characteristic distribution of Cys,
i.e. Cys-X-Cys and spectroscopic manifestations characteristic of metal
thiolate clusters.
A MT family subsumes MTs which share a particular set of sequence specific
characters. Members of a family can belong to only one family and are thought
to be evolutionary related. The inclusion of an MT in a family presupposes
that its amino acid sequence is alignable with that of all members. A common
and exclusive sequence pattern, a profile and a phylogenetic tree can
therefore be connected with each family. Each family is identified by its
number and its taxonomic range. An example is Family 1: vertebrate MTs.
A MT subfamily contains MTs which in addition to the family characters share a
set of more stringent phylogenetic features. These extra criteria are usually
specific monophyletic relationships among the sequences of proteins and/or of
nucleotide segments in the genes (5' or 3' untranscribed portion of the genes,
5' or 3' untranslated portions of the nucleotide sequences, exons, introns).
If relevant other differentiating criteria can also be included, such as
presence, conservation or repetition of sequence patterns. A subfamily is
usually abbreviated with a letter character followed, if necessary, with an
arabic number. An example is m1: mammalian MT-1.
A MT subgroup represents, as a result of statistically validated phylogenetic
analyses, a branch of MT sequences of a subfamily which is clearly
distinguishable in a tree by its monophyletic character. An example is m2U2:
ungulate MT-2, subgroup of the m2 subfamily.
Isoforms or allelic forms are specifiable as members of subgroups, subfamilies
and families. They are named using the nomenclature system defined in Kojima
et al. (submitted), i.e. human MT-1E.
In addition, in cases where it is justifiable, one can define clans. A clan is
a set of partial or total amino acid or polynucleotide sequences, subgroups,
subfamilies, families or combinations of them which share characters not
defined by the above classification criteria. They can be related to common
spatial structure, thermodynamic properties, metal binding properties,
functionally related characters or other relevant features. A clan is defined
by the property common to its members. The abbreviation should reflect this
property.
-----------------------------------------------------------------------
Copyrighted by the UniProt Consortium, see http://www.uniprot.org/terms
Distributed under the Creative Commons Attribution-NoDerivs License
-----------------------------------------------------------------------