A CLADISTIC-ANALYSIS OF THE EVOLUTIONARY RELATIONSHIPS OF THE MEMBERSOF THE TYROSINASE GENE FAMILY USING SEQUENCE DATA

Recently, DNA sequence data have been published on tyrosinase and tyro sinase-related proteins (TRPs) in a wide variety of vertebrates rangin g from Rana to Home, These proteins are in turn members of a larger fa mily of binuclear copper-binding proteins, which all contain two highl y conserved copper-binding domains. This gene family also includes tyr osinases from fungi and bacteria as well as arthropodan and molluscan hemocyanins. Parsimony-based alignment and tree construction algorithm s (Malign, v1.85 and PAUP, 3.1.1) were used to analyze the diversifica tion of both the evolutionarily conserved copper-binding domains in co pper-binding proteins in general as well as the diversification of the vertebrate tyrosinase gene family more specifically. These analyses s how that the diversification of the vertebrate tyrosinase gene family minimally predates the diversification of vertebrates. Vertebrate tyro sinases proper first diverged from an ancestral tyrosinase-related pro tein (TRP) that then subsequently diverged to form tyrosinase-related protein-is (TRP-1s) and tyrosinase-related protein-2s (TRP-2s).