| Type: | Family | Name: | Metallothionein, family 14, prokaryote |
| Description: | Metallothioneins (MT) are small proteins that bind heavy metals, such as zinc, copper, cadmium and nickel. They have a high content of cysteine residues that bind the metal ions through clusters of thiolate bonds [, , ]. An empirical classification into three classes was proposed by Kojima [], with class III MTs including atypical polypeptides composed of gamma-glutamylcysteinyl units. Class I and class II MTs (the proteinaceous sequences) have now been grouped into families of phylogenetically-related and thus alignable sequences. The MT superfamily is subdivided into families, subfamilies, subgroups, and isolated isoforms and alleles. The metallothionein superfamily comprises all polypeptides that resemble equine renal metallothionein in several respects [], 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. Fifteen MT families have been characterised, each family being identified by its number and its taxonomic range.Family 14 consists of prokaryota MTs. Its members are recognised by the sequence pattern K-C-A-C-x(2)-C-L-C.The taxonomic range of the members extends to cyanobacteria. Known characteristics are: 53 to 56 AAs; 9 conserved Cys; one conserved tyrosine residue; one conserved histidine residue; contain other unusual residues. | Short Name: | Metalthion_fam14_prok |
