title: Synthesis and activity of Xenopus laevis oocyte tyrosinase.
abstract: This study investigates the mechanisms that control pigment synthesis in Xenopus laevis oocytes. Although we find the molecular weight of oocyte tyrosinase to be similar to that of amphibian skin, we were unable to increase its activity by proteases or detergents, as has been reported for skin tyrosinase. On the other hand, by measuring the activity of polysomal-bound enzyme, we were able to correlate increased tyrosinase activity with increased levels of enzyme synthesis. We therefore suggest that in oocytes, the activity of tyrosinase is primarily dependent on its synthesis, whereas in skin, the rate-limiting step is the post-translational activation of the enzyme. We speculate on these differences in relation to the functional role of melanin in skin and oocytes.
authors.affiliation: Department of Anatomy and Cell Biology, University of Cape Town Medical School, South Africa.
authors.forename: S H
authors.initials: SH
authors.lastname: Kidson
authors.forename: B C
authors.initials: BC
authors.lastname: Fabian
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000096:biosynthesis*; D002498:Centrifugation; D002918:Chymotrypsin / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008544:Melanocytes / Q000201:enzymology; D008970:Molecular Weight; D014442:Monophenol Monooxygenase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000201:enzymology*; D010206:Papain / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D012867:Skin / Q000201:enzymology; D014158:Transcription, Genetic; D014357:Trypsin / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D003902:Detergents; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D002918:Chymotrypsin; D014357:Trypsin; D010206:Papain