Biomaterial Database

Mammalian tyrosinase: biosynthesis, processing, and modulation by melanocyte-stimulating hormone. 1988

M Jiménez, and K Kameyama, and W L Maloy, and Y Tomita, and V J Hearing

Laboratory of Cell Biology, National Cancer Institute, Bethesda, MD 20892.

We have examined the rate of synthesis and degradation of tyrosinase (monophenol, 3,4-dihydroxyphenylalanine:oxygen oxidoreductase, EC 1.14.18.1), the critical enzyme involved in mammalian pigmentation, using pulse-chase metabolic labeling of murine melanoma cells and immunoprecipitation of protein extracts with antibodies directed specifically against the enzyme. We have found that tyrosinase is synthesized and glycosylated within melanocytes rapidly, since significant quantities of pulse-labeled enzyme could be detected within 30 min. The maximum amount of enzyme was processed within 4 hr, and the t1/2 of tyrosinase in vivo was 10 hr (compared to 120 hr with purified enzyme), suggesting that tyrosinase activity in melanocytes is at least in part regulated by rapid synthesis and active degradation. We also have examined the melanogenic stimulation caused by melanocyte-stimulating hormone, using metabolic labeling, radiometric assays, and immunofluorescence techniques; responding cells increased their melanogenic potential more than 7-fold within 4 days without increasing their levels of tyrosinase synthesis. The results demonstrate that a pool of inactive tyrosinase exists in melanocytes and that rapid increases in enzyme activity elicited by melanocyte-stimulating hormone reflect an alteration in the activity of a preexisting pool of intracellular tyrosinase.

UI	MeSH Term	Description	Entries
D007158	Immunologic Techniques	Techniques used to demonstrate or measure an immune response, and to identify or measure antigens using antibodies.	Antibody Dissociation,Immunologic Technic,Immunologic Technics,Immunologic Technique,Immunological Technics,Immunological Techniques,Technic, Immunologic,Technics, Immunologic,Technique, Immunologic,Techniques, Immunologic,Antibody Dissociations,Dissociation, Antibody,Dissociations, Antibody,Immunological Technic,Immunological Technique,Technic, Immunological,Technics, Immunological,Technique, Immunological,Techniques, Immunological
D008543	Melanins	Insoluble polymers of TYROSINE derivatives found in and causing darkness in skin (SKIN PIGMENTATION), hair, and feathers providing protection against SUNBURN induced by SUNLIGHT. CAROTENES contribute yellow and red coloration.	Allomelanins,Melanin,Phaeomelanins
D008544	Melanocytes	Mammalian pigment cells that produce MELANINS, pigments found mainly in the EPIDERMIS, but also in the eyes and the hair, by a process called melanogenesis. Coloration can be altered by the number of melanocytes or the amount of pigment produced and stored in the organelles called MELANOSOMES. The large non-mammalian melanin-containing cells are called MELANOPHORES.	Melanocyte
D008545	Melanoma	A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world. (Stedman, 25th ed; from Rook et al., Textbook of Dermatology, 4th ed, p2445)	Malignant Melanoma,Malignant Melanomas,Melanoma, Malignant,Melanomas,Melanomas, Malignant
D009074	Melanocyte-Stimulating Hormones	Peptides with the ability to stimulate pigmented cells MELANOCYTES in mammals and MELANOPHORES in lower vertebrates. By stimulating the synthesis and distribution of MELANIN in these pigmented cells, they increase coloration of skin and other tissue. MSHs, derived from pro-opiomelanocortin (POMC), are produced by MELANOTROPHS in the INTERMEDIATE LOBE OF PITUITARY; CORTICOTROPHS in the ANTERIOR LOBE OF PITUITARY, and the hypothalamic neurons in the ARCUATE NUCLEUS OF HYPOTHALAMUS.	MSH,Melanocyte Stimulating Hormone,Melanocyte-Stimulating Hormone,Melanophore Stimulating Hormone,Melanotropin,MSH (Melanocyte-Stimulating Hormones),Melanophore-Stimulating Hormone,Hormone, Melanocyte Stimulating,Hormone, Melanocyte-Stimulating,Hormone, Melanophore Stimulating,Melanocyte Stimulating Hormones,Stimulating Hormone, Melanocyte,Stimulating Hormone, Melanophore
D011499	Protein Processing, Post-Translational	Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.	Amino Acid Modification, Post-Translational,Post-Translational Modification,Post-Translational Protein Modification,Posttranslational Modification,Protein Modification, Post-Translational,Amino Acid Modification, Posttranslational,Post-Translational Amino Acid Modification,Post-Translational Modifications,Post-Translational Protein Processing,Posttranslational Amino Acid Modification,Posttranslational Modifications,Posttranslational Protein Processing,Protein Processing, Post Translational,Protein Processing, Posttranslational,Amino Acid Modification, Post Translational,Modification, Post-Translational,Modification, Post-Translational Protein,Modification, Posttranslational,Modifications, Post-Translational,Modifications, Post-Translational Protein,Modifications, Posttranslational,Post Translational Amino Acid Modification,Post Translational Modification,Post Translational Modifications,Post Translational Protein Modification,Post Translational Protein Processing,Post-Translational Protein Modifications,Processing, Post-Translational Protein,Processing, Posttranslational Protein,Protein Modification, Post Translational,Protein Modifications, Post-Translational
D002455	Cell Division	The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.	M Phase,Cell Division Phase,Cell Divisions,Division Phase, Cell,Division, Cell,Divisions, Cell,M Phases,Phase, Cell Division,Phase, M,Phases, M
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004156	Catechol Oxidase	An enzyme of the oxidoreductase class that catalyzes the reaction between catechol and oxygen to yield benzoquinone and water. It is a complex of copper-containing proteins that acts also on a variety of substituted catechols. EC 1.10.3.1.	Diphenol Oxidases,Diphenol Oxidase,Polyphenol Oxidase,Polyphenoloxidase,Oxidase, Catechol,Oxidase, Diphenol,Oxidase, Polyphenol,Oxidases, Diphenol
D006031	Glycosylation	The synthetic chemistry reaction or enzymatic reaction of adding carbohydrate or glycosyl groups. GLYCOSYLTRANSFERASES carry out the enzymatic glycosylation reactions. The spontaneous, non-enzymatic attachment of reducing sugars to free amino groups in proteins, lipids, or nucleic acids is called GLYCATION (see MAILLARD REACTION).	Protein Glycosylation,Glycosylation, Protein