The yeast Pma1 ATPase is mainly activated at the post-transcriptional level by glucose metabolism [8]. This activation is mediated by downregulation of the inhibitory casein kinase I (encoded by YCK1 and YCK2 genes) [9] and upregulation of the activating protein kinase Ptk2 [10]. Trk is also regulated at the post-transcriptional level, being activated by protein kinases Hal4–Hal5 in response to K+ starvation [11], and inhibited by protein kinase Sky1 [12,13]. Trk is also activated by the calcium-dependent protein phosphatase calcineurin [14] and inhibited by the protein phosphatase Ppz encoded by PPZ1 and PPZ2 genes [15]. In addition, the K+ -uptake system is activated by glucose metabolism, but nothing is known about the mechanism