Protein phosphorylation in the nervous system.
Item
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Title
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Protein phosphorylation in the nervous system.
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Identifier
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AAI9959243
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identifier
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9959243
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Creator
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Yang, Huiai.
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Contributor
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Advisers: Yigal H. Ehrlich | Probal Banerjee
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Neuroscience
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Abstract
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Ecto-protein kinases are enzymes which are responsible for protein phosphorylation occurring in the matrix. Extracellular phosphorylation has been found to be associated with the growth and transformation of parasites, and its involvement in the formation of bone tissues has been discovered. Using cultured telencephalons from seven-day chicken embryos, we have investigated the role of extracellular phosphorylation in nervous system.;Extracellular phosphorylation assays performed on attached cells have revealed several proteins as substrates of ecto-protein kinases. When antibodies generated against protein kinase C isozymes were added to the assay buffer, the PKC delta antibody selectively inhibited the phosphorylation of two proteins with apparent molecular weights of 12 and 13 kilodatons. This suggests that there is a PKC delta-like ecto-protein kinase located on the surface of cultured chicken telencephalons, and that there is a novel signal transduction pathway mediated by extracellular phosphorylation in the nervous system.;Similar to the regulation of extracellular phosphorylation by ecto-protein kinases, important cellular events such as mitosis and transformation are regulated by specific intracellular protein kinases. Raf-1 is such a kinase which is also a key player in MAP kinase-mediated mitosis and transformation. Additionally, its involvement in apoptosis has been recently observed.;Since Raf-1 phosphorylation plays a key role in regulating the MAP kinase pathway, we investigated the effect of 8-OH-DPAT, a serotonin 1A receptor agonist, on Raf-1 phosphorylation in a hippocampal hybrid neuroblastoma cell line (HN2-5). We also investigated the interactions of phosphorylated Raf-1 with some proteins of the apoptotic pathway. Our results showed that though increased Raf-1 phosphorylation was not detected by 1-D gel, further resolution with the 2-D gel did reveal elevated Raf-1 phosphorylation in cells treated with 8-OH-DPAT. Immunoprecipitation studies showed that the phosphorylated Raf-1 molecule is co-immunoprecipitated with antibodies against caspase 8 and Bad, but not with an antibody against Bcl-2. Caspase 8 belongs to a family of cystein proteases, which are activated by apoptotic signals. Bad and Bcl-2 belong to the Bcl-2 family of proto-oncogenes, which regulate mitochondrial functions and apoptosis. The formation of Raf-1-caspase 8 and Raf-1-Bad complexes suggest that Raf-1 might be also involved in regulating the apoptotic pathway.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
