pp60c-src in human melanocytes and melanoma cells exhibits elevated specific activity and reduced tyrosine 530 phosphorylation compared to human fibroblast pp60c-src. 1992

T J O'Connor, and E Neufeld, and J Bechberger, and D J Fujita
Department of Medical Biochemistry, University of Calgary, Health Sciences Center, Alberta, Canada.

Elevated levels of pp60c-src tyrosine kinase activity have been implicated in both tumorigenesis and cell differentiation. We have found a 2- to 4-fold elevation in pp60c-src specific activity in certain human melanoma cell lines compared to human foreskin fibroblasts. This activation of pp60c-src did not appear to be related to melanoma tumor progression, because when normal human epidermal melanocytes were examined, it was found that they contained pp60c-src having a 7-fold elevation in specific activity compared to pp60c-src from human fibroblasts. It was determined that pp60c-src from melanocytes was not the neuronal form, pp60c-src+. Melanocyte pp60c-src exhibited a reduced level of phosphorylation on its carboxyl-terminal regulatory site, tyrosine 530, which might be responsible for its elevated specific activity. These results suggest that, in melanocytes, regulation of tyrosine 530 phosphorylation-dephosphorylation favors activation of pp60c-src. This activation may be involved in the growth, differentiation, or function of human melanocytes.

UI MeSH Term Description Entries
D007527 Isoenzymes Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics. Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D008297 Male Males
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
D009363 Neoplasm Proteins Proteins whose abnormal expression (gain or loss) are associated with the development, growth, or progression of NEOPLASMS. Some neoplasm proteins are tumor antigens (ANTIGENS, NEOPLASM), i.e. they induce an immune reaction to their tumor. Many neoplasm proteins have been characterized and are used as tumor markers (BIOMARKERS, TUMOR) when they are detectable in cells and body fluids as monitors for the presence or growth of tumors. Abnormal expression of ONCOGENE PROTEINS is involved in neoplastic transformation, whereas the loss of expression of TUMOR SUPPRESSOR PROTEINS is involved with the loss of growth control and progression of the neoplasm. Proteins, Neoplasm
D009474 Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM. Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D010766 Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Phosphorylations
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
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D005134 Eye Neoplasms Tumors or cancer of the EYE. Cancer of Eye,Eye Cancer,Cancer of the Eye,Neoplasms, Eye,Cancer, Eye,Cancers, Eye,Eye Cancers,Eye Neoplasm,Neoplasm, Eye

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