Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

monophenol monooxygenase

Name from literature


Pathway from literature

melanin synthesis

Pathway from KEGG

Metabolism of Cofactors and Vitamins; Riboflavin metabolism; map00740

Biosynthesis of Secondary Metabolites; Alkaloid biosynthesis I; map00950

Cellular Processes; Endocrine System; Melanogenesis; map04916

Amino Acid Metabolism; Tyrosine metabolism; map00350


Human (9606)

Genome localization

11q14-q21[7299 ],


A group of copper proteins that also catalyse the reaction of EC catechol oxidase, if only 1,2-benzenediols are available as substrate.

Rate-limiting Description

"To distinguish these two possibilities, the present study examined the effects of latanoprost on tyrosinase activity (the rate-limiting step for melanin synthesis) and mitotic index of cultured melanoma lines." (10870514)

"Tyrosinase is a copper containing enzyme and is responsible for catalyzing the rate limiting step in melanin biosynthesis, the hydroxylation of tyrosine to dopaquinone." (10671066)

Regulatory Information

Upstream transcription factor


Regulatory type


key enzyme;

"Tyrosinase (EC is the key enzyme of melanin pigment formation and it is unclear whether it is synthesized in human postnatal retinal pigment epithelium (RPE). " (17318568)

transcriptional factor;DCoH(5092)/HNF-1(6927)

"Data reveal DCoH/HNF-1 alpha expression and transcriptional activity in human epidermal melanocytes in vitro and in situ and identified tyrosinase, the key enzyme for pigmentation, as a new transcriptional target." (12565907)


"These results suggest that phosphorylation of tyrosinase by PKC-beta induces a complex formation between tyrosinase and TRP-1." (14623273)


"data show that chloride ion inhibited tyrosinase in a competitive manner" (17718595)



transcriptional factor;MITF(4286)

"These results indicate that MITF is a cell-type-specific factor that is capable of activating transcription of the tyrosinase gene." (7969144)

transcriptional factor;RB1(5925)

"Mitf cooperates with Rb1 and activates p21Cip1 expression to regulate cell cycle progression." (15716956)

Gene ontology

Gene ontology

GO:0006726 (P) eye pigment biosynthetic process [P14679 ];
GO:0007601 (P) visual perception [P14679 ];
GO:0042803 (F) protein homodimerization activity [P14679 ];
GO:0033162 (C) melanosome membrane [P14679 ];
GO:0046982 (F) protein heterodimerization activity [P14679 ];
GO:0007605 (P) sensory perception of sound [P14679 ];
GO:0005798 (C) Golgi-associated vesicle [P14679 ];
GO:0006583 (P) melanin biosynthetic process from tyrosine [P14679 ];
GO:0048471 (C) perinuclear region of cytoplasm [P14679 ];
GO:0016021 (C) integral to membrane [P14679 ];
GO:0005507 (F) copper ion binding [P14679 ];
GO:0005764 (C) lysosome [P14679 ];
GO:0004503 (F) monophenol monooxygenase activity [P14679 ];
GO:0055114 (P) oxidation reduction [P14679 ];

Subcellular localization


cell membrane [P14679 ];

cytoplasm [P14679 ];

Disease relevance


Defects in TYR are the cause of oculocutaneous albinism type I temperature-sensitive (OCA-ITS) [MIM:606952]. OCA-ITS patients have white axillary and scalp hair and pigmented arm and leg hair [P14679 ];

Defects in TYR are the cause of oculocutaneous albinism type IB (OCA-IB) [MIM:606952];
also known as albinism yellow mutant type. OCA-IB patients have white hair at birth that rapidly turns yellow or blond. They manifest the development of minimal-to-moderate amounts of cutaneous and ocular pigment [P14679 ];

Defects in TYR are the cause of oculocutaneous albinism type IA (OCA-IA) [MIM:203100]. OCA-I, also known as tyrosinase negative oculocutaneous albinism, is an autosomal recessive disorder characterized by absence of pigment in hair, skin and eyes. OCA-I is divided into 2 types: type IA, characterized by complete lack of tyrosinase activity due to production of an inactive enzyme, and type IB characterized by reduced activity of tyrosinase. OCA-IA patients presents with the life-long absence of melanin pigment after birth and manifest increased sensitivity to ultraviolet radiation and to predisposition to skin cancer [P14679 ];




Entrez Gene




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  Last Modified: 2009-03-24  
  Design by Zhao Min