Modulation of Arabidopis K⁺ channel activities by modification of the C-terminal region

Abstract

The transport and gating activities of K⁺ channels are thought to be regulated by multiple posttranslational modifications of the C-terminal region, such as phosphorylation and binding of cyclic nucleotides. These phenomena indicate that multiple signaling pathways likely exist for channel regulation in response to various environmental stresses. We previously identified the phosphorylation target sites of the Arabidopis Shaker-type K⁺ channel, KAT1, and found that the modification of one of these sites strongly modulates K⁺ channel activities of KAT1 expressed in Xenopus oocytes and yeast (Sato et. al. Biochem. J. 2009). The phopshorylation site is highly conserved between all Arabidopis K⁺ channels. Thus, we examined the phosphorylation of the other Arabidopsis K⁺ channels, and the effect of modification of the conserved site on the K⁺ channel activities. We will also discuss the regulatory mechanism involving the modification of C-terminal region.