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Biochim Biophys Acta. 2006 Feb;1758(2):164-70. Epub 2006 Feb 8.

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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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.


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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