Tyrosinase family
tyrosinase family
The three protein-coding members of the tyrosinase family play a crucial role in determining melanin production and coloration of animal pigment cells. These proteins are anchored to the melanosomal membrane through a C-terminal fragment. They share approximately 40% amino acid identity and the same structural features, including a signal peptide, a Cys-rich domain, two metal binding sites and a transmembrane domain. Tyrosinase (TYR) catalyzes the first two steps of the Raper–Mason pathway, the hydroxylation of l-tyrosine to l-DOPA and the subsequent oxidation of l-DOPA to l-dopaquinone. The first activity is called tyrosine hydroxylase, and the second one o-diphenol oxidase, catechol oxidase or DOPA oxidase. Dopachrome tautomerase (DCT, previously TYRP2) catalyzes the conversion of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA). TYRP1 is abundant in melanocytes and mutations can result in oculocutaneous albinism type 3 (OCA3) but the precise role of TYRP1 in human melanogenesis remains unclear.