Abstract
The transport and gating activities of K+ channels are thought to be regulated by posttranslational modification. Several putative phosphorylation target residues exist in the cytosolic region of the Arabidopis K+ channel, KAT1. In this study, in vitro kinase assays demonstrated that the C-terminal region of KAT1 acts as a phosphorylation target for an Arabidopsis protein kinase. We have also examined the correlation between KAT1 phosphorylation and channel activity using two-electrode voltage clamp analysis in Xenopus oocytes. In these experiments, KAT1 channel activity was measured both pre- and post-activation of protein kinases in the Xenopus oocytes. Several KAT1 variants have now been generated that contain point mutations at putative phosphorylation target sites. The K+transport activities of these variants are also being examined in our Xenopus oocyte system and compared to that of wild-type KAT1.
