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* Tyrosinase signatures *
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Tyrosinase (EC 1.14.18.1) [1] is  a  copper  monooxygenases that catalyzes the
hydroxylation of  monophenols and the oxidation  of  o-diphenols to o-quinols.
This enzyme, found in prokaryotes as well as in eukaryotes, is involved in the
formation of pigments such as melanins and other polyphenolic compounds.

Tyrosinase binds two copper ions (CuA and CuB). Each of the two copper ion has
been shown [2] to be bound by three conserved histidines residues. The regions
around these copper-binding ligands are well conserved and also shared by some
hemocyanins, which are copper-containing oxygen carriers from the hemolymph of
many molluscs and arthropods [3,4].

At least two proteins related to tyrosinase are known to exist in mammals:

 - TRP-1 (also known as gp75, or  tyrosinase-related protein (trp)), which has
   recently been shown [5] to express a catalase-type activity.
 - TRP-2 [6],   which  is  the   melanogenic  enzyme   DOPAchrome  tautomerase
   (EC 5.3.3.12)   that   catalyzes  the  conversion  of  DOPAchrome  to  5,6-
   dihydroxyindole-2-carboxylic acid (DHICA).

The Caenorhabditis elegans hypothetical protein C02C2.1 also belongs to to the
tyrosine family.

We have derived two signature patterns for  tyrosinases and  related proteins.
The first one contains two of the histidines that bind CuA, and is  located in
the N-terminal section of tyrosinase.  The second pattern contains a histidine
that binds CuB, that pattern is located in the central section of the enzyme.

-Consensus pattern: H-x(4)-F-[LIVMT]-x-W-H-R-x(2)-[LM]-x(3)-E
                    [The two H's are copper ligands]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Consensus pattern: D-P-x-F-[LIVMFYW]-x(2)-H-x(3)-D
                    [H is a copper ligand]
-Sequences known to belong to this class detected by the pattern: ALL the
 tyrosinases as well as all the hemocyanins.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Last update: June 1994 / Patterns and text revised.

[ 1] Lerch K.
     Prog. Clin. Biol. Res. 256:85-98(1988).
[ 2] Jackman M.P., Hajnal A., Lerch K.
     Biochem. J. 274:707-713(1991).
[ 3] Linzen B.
     Naturwissenschaften 76:206-211(1989).
[ 4] Lang W.H., van Holde K.E.
     Proc. Natl. Acad. Sci. U.S.A. 88:244-248(1991).
[ 5] Halaban R., Moellmann G.
     Proc. Natl. Acad. Sci. U.S.A. 87:4809-4813(1990).
[ 6] Jackson I.J., Chambers D.M., Tsukamoto K., Copeland N.G., Gilbert D.J.,
     Jenkins N.A., Hearing V.
     EMBO J. 11:527-535(1992).