Yeast protein kinase Ptk2 localizes at the plasma membrane and phosphorylates in vitro the C-terminal peptide of the H-ATPase |
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Authors: | Pilar Eraso |
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Institution: | Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid and Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas, Arturo Duperier, 4, 28029 Madrid, Spain |
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Abstract: | Glucose triggers posttranslational modifications that increase the activity of the Saccharomyces cerevisiae plasma membrane H+-ATPase (Pma1). Glucose activation of yeast H+-ATPase results from the change in two kinetic parameters: an increase in the affinity of the enzyme for ATP, depending on Ser899, and an increase in the Vmax involving Thr912. Our previous studies suggested that Ptk2 mediates the Ser899-dependent part of the activation. In this study we find that Ptk2 localized to the plasma membrane in a Triton X-100 insoluble fraction. In vitro phosphorylation assays using a recombinant GST-fusion protein comprising 30 C-terminal amino acids of Pma1 suggest that Ser899 is phosphorylated by Ptk2. Furthermore, we show that the Ptk2 carboxyl terminus is essential for glucose-dependent Pma1 activation and for the phosphorylation of Ser899. |
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Keywords: | H+-ATPase Plasma membrane Ptk2 Phosphorylation Glucose activation |
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