Regulation of the cytosolic and melanosome-bound tyrosinase activities in harding-passey mouse melanoma

Analysis of Mammalian Pigmentation at the Molecular Level

“…Melanization is regulated at the enzymatic level in many different ways. Tyrosinase synthesis, degradation, and activation have been shown to play a role in melanin production, and the rate of the enzyme's pro-cessing and/or delivery to the melanosome also affects its activity [Fuller et al, 1987;Halaban et al, 1983Halaban et al, , 1984Jimhez et al, 19881. In addition, tyrosinase inhibitors and activators have been reported, and recently the role of post-tyrosinase factors andlor enzymes in melanogenesis became more apparent [Barber et al, 1984[Barber et al, , 1985Garcia-Borron et al, 1985a;Korner and Pawelek, 1980;Pawelek et al, 19801. Lastly, there are miscellaneous other parameters affecting enzyme activity and melanin synthesis that may be important, such as post-translational glycosylation, the availability of substrates and cofactors, the intramelanosomal pH, and so on [Devi et al, 1987;Garcia-Borron et al, 1985b;Garcia-Canovas et al, 1982;Halaban et al, 1988;Martinez et al, 1987;Tripathi et al, 19881. It should be pointed out that although melanogenesis was initially attractive for study because of its simplicity, the complexities of the processes involved in the regulation and production of melanin are becoming more intriguing each year [for recent reviews, see Fuller et al, 1987;Hearing, 1987;Hearing and JimBnez, 1987;Laskin and Piccinini, 19861. Although there has been much descriptive work which has made progress in understanding the mechanisms involved in the regulation of melanogenesis in mammals at all these levels, it has only been with the recent advent of molecular biology that it has become possible to elucidate the definitive role of the different pigmentrelated loci in these processes.…”