DEFAR - Departamento de Farmácia

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/530

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1994 - 199912000 - 20051

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Assunto: search.filters.subject.Protein kinase C

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    Possible involvement of a phosphatidylinositol-type signaling pathway in glucose-induced activation of plasma membrane ATPase and cellular proton in the yeast Sacchamyces cerevisiae.
    (1994) Brandão, Rogélio Lopes; Rocha, Neuza Maria de Magalhaes; Alijo, Rafael; Ramos, José; Thevelein, Johan Maria
    Addition of glucose to cells of the yeast Saccharomyces cerevisiae causes rapid activation of plasma membrane H+-ATPase and a stimulation of cellular H ÷ extrusion. We show that addition of diacylglycerol and other activators of protein kinase C to intact cells also activates the H+-ATPase and causes at the same time a stimulation of H ÷ extrusion from the cells. Both effects are reversed by addition of staurosporine, a protein kinase C inhibitor. Addition of staurosporine or calmidazolium, an inhibitor of Ca2+/calmodulin-dependent protein kinases, separately, causes a partial inhibition of glucose-induced H+-ATPase activation and stimulation of cellular H + extrusion; together they cause a more potent inhibition. Addition of neomycin, which complexes with phosphatidylinositol 4,5-bisphosphate, or addition of compound 48/80, a phospholipase C inhibitor, also causes near complete inhibition. Diacylglycerol and other protein kinase C activators had no effect on the activity of the K+-uptake system and the activity of trehalase and glucose-induced activation of the K+-uptake system and trehalase was not inhibited by neomycin, supporting the specificity of the effects observed on the H+-ATPase. The results support a model in which glucose-induced activation of H+-ATPase is mediated by a phosphatidylinositol-type signaling pathway triggering phosphorylation of the enzyme both by protein kinase C and one or more Ca2+/calmodulin-dependent protein kinases.
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    Deficiency of Pkc1 activity affects glycerol metabolism in Saccharomices cerevisiae.
    (2005) Gomes, Katia das Neves; Freitas, Suzy Magaly Alves Cabral de; Pais, Thiago Martins; Fietto, Juliana Lopes Rangel; Totola, Antonio Helvecio; Arantes, Rosa Maria Esteves; Martins, António; Lucas, Cândida Manuel Ribeiro Simões; Schuller, Dorit; Casal, Margarida; Castro, Ieso de Miranda; Fietto, Luciano Gomes; Rogelio, Lopes Brandão
    Protein kinase C is apparently involved in the control of many cellular systems: the cell wall integrity pathway, the synthesis of ribosomes, the appropriated reallocation of transcription factors under specific stress conditions and also the regulation of N-glycosylation activity. All these observations suggest the existence of additional targets not yet identified. In the context of the control of carbon metabolism, previous data had demonstrated that Pkc1p might play a central role in the control of cellular growth and metabolism in yeast. In particular, it has been suggested that it might be involved in the derepression of genes under glucose-repression by driving an appropriated subcellular localization of transcriptional factors, such as Mig1p. In this work, we show that a pkc1D mutant is unable to grow on glycerol because it cannot perform the derepression of the GUT1 gene that encodes glycerol kinase. Additionally, active transport is also partially affected. Using this phenotype, we were able to isolate a new pkc1D revertant. We also isolated two transformants identified as the nuclear exportin Msn5 and the histone deacetylase Hos2 extragenic suppressors of this mutation. Based on these results, we postulate that Pkc1p may be involved in the control of the cellular localization and/or regulation of the activity of nuclear proteins implicated in gene expression.