Sequence analysis of mouse tyrosinase cDNA and the effect of melanotropin on its gene expression

Using human tyrosinase cDNA as a probe, a mouse tyrosinase cDNA clone representing approximately 75% of the tyrosinase coding region and a mouse genomic clone which includes the tyrosinase 5' coding sequences were isolated: nucleotide and deduced amino acid sequence of the mouse tyrosinase gene were determined from these clones. The predicted amino acid sequence revealed that the mouse tyrosinase is composed of 533 amino acids with a molecular weight of 60,536. The deduced protein contains 6 potential N-glycosylation sites, two cysteine- and two histidine-rich regions which may serve as copper-binding sites, a potential signal and transmembrane sequences. The mouse and human tyrosinase nucleotide and deduced amino acid sequences are approximately 81% homologous. The level of mouse tyrosinase mRNA was elevated after stimulation of Cloudman S-91 melanoma cells with melanotropin and isobutylmethylxanthine and the level of transcript reflected that of tyrosinase activity and melanin content in the cells.