CELLULAR LOCALIZATION OF TYROSINASE IN HUMAN MALIGNANT-MELANOMA CELL LINES

[摘要] Human malignant melanocytes show characteristic morphologic modifications which are particularly evident in their specific organelles: melanosomes. These modifications are conserved in cell culture. The ultrastructural localization of tyrosinase, the enzyme which converts tyrosine and dopa into melanin, was determined in 13 human melanoma cell lines. The different cell lines possessed 4 distribution patterns of melanin synthesis based on dopa oxidase activity. The 2 first pathways, which involve the Golgi apparatus, seem to differ by the amount of enzyme within this organelle. The 3rd pathway involves the smooth endoplasmic reticulum, whereas tyrosinase is visible only in vesicles in the 4th. Some cells synthesize the enzyme in the manner observed in very early embryos.