title: gamma-Glutamyl transpeptidase, tyrosinase, and 5-S-cysteinyldopa production in melanoma cells.
abstract: The distribution of gamma-glutamyl transpeptidase (gamma-GTP), tyrosinase, and 5-S-cysteinyldopa (5-S-CD) within melanoma cells has been studied in vitro as well as in vivo. Sodium periodate treatment of intact B-16 melanoma cells has been found to inhibit gamma-GTP present as an ectoenzyme. However, these periodate-treated cells in the presence of 10(-5) M dopa and glutathione have been found to continue to secrete large quantities of 5-S-CD in their medium. The large-granule fraction of Greene's melanotic melanoma contains substantial amounts of both tyrosinase and gamma-GTP. However, further separation of the large-granule fraction into sub-fractions indicates that tyrosinase and gamma-GTP seem to co-exist with premelanosome. It is suggested that glutathione-dependent t-S-CD genesis proceeds within premelanosomes through the formation of glutathione-dopa. The excess of glutathione-dopa and 5-S-CD, unutilized for pheomelanin formation overglow into the cytoplasm.
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000378:metabolism*; D006224:Cricetinae; D003548:Cysteinyldopa / Q000378:metabolism*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives*; D005978:Glutathione / Q000494:pharmacology; D008545:Melanoma / Q000378:metabolism*; D008647:Mesocricetus; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010504:Periodic Acid / Q000494:pharmacology; D014018:Tissue Distribution; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D010504:Periodic Acid; D003548:Cysteinyldopa; D004295:Dihydroxyphenylalanine; C009288:metaperiodate; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D005723:gamma-Glutamyltransferase; D005978:Glutathione