Tyrosinase
Synonym(s)
DefinitionThis section has been translated automatically.
Tyrosinase is a copper-containing protein (enzyme - oxidoreductase) with 529 amino acids, which is widely distributed in plants and animals. In humans, tyrosinase is involved in the synthesis of melanin. It is activated by UV light. The coding human tyrosinase gene (TYRP-1 gene) is located on the long arm of chromosome 11 (11q14-21).
General informationThis section has been translated automatically.
The biosynthesis of melanin begins with the hydroxylation of the amino acid LTyrosine to dihydroxyphenylalanine (Dopa) and the oxidation of Dopa to Dopaquinone. These reactions are catalysed by the enzyme tyrosinase, which is the speed determining enzyme of the whole reaction.
The differentiated, melanin-loaded pigment polymer is deposited on a protein matrix within the melanosomes. In the skin and hair, the melanosomes are then transported via the dendrites of the melanocytes to the keratinocytes. In the keratinocytes, the melanosomes are stored in the form of a cap on the side of the cell nucleus facing the skin surface. The cell nucleus and the DNA in it are thus protected from the harmful effects of UV radiation.
Note(s)This section has been translated automatically.
Mutations in the TYR gene are responsible for oculocutaneous albinism type 1 (OCA1). A variant of Waardenburg syndrome type 2 is caused by an interaction of a mutation of the tyrosinase locus (R402Q) with a mutation of the Mitf gene.
Copper deficiency (Menkes syndrome) therefore leads to reduced enzyme formation and reduced pigmentation.
Glutathione has been shown to inhibit the activity of tyrosinase.
LiteratureThis section has been translated automatically.
- Barton DE et al. (1988) Human tyrosinase gene, mapped to chromosome 11 (q14-q21), defines second region of homology with mouse chromosome 7. Genomics 3:1724
- Boissy RE et al. (1997) Molecular basis of congenital hypopigmentary disorders in humans: a review. Pigment Cell Res 10:12-24
- Passmore LA et al. (1999) Novel and recurrent mutations in the tyrosinase gene and the P gene in the German albino population . Hum Genet 105:200-210
Sonthalia S et al. (2016) Glutathione as a skin whitening agent: Facts, myths, evidence and controversies. Indian J Dermatol Venereol Leprol 822: 62-72.
Villarama CD et al. (2005) Glutathione as a depigmenting agent: An overview. Int J Cosmet Sci 27:147-153.