Abstract
In Arabidopsis thaliana, the AHK4/CRE1/WOL1 His-kinase and AHK2/3 homologs have been shown to function as cytokinin sensors. These cytokinin sensors presumably function as histidine kinase (His-kinase), involved in His-Asp phosphorelay signal transduction pathway. His-Asp phosphorelay pathway is typically made up of His-kinase, histidine containing phosphotransmitter (HPt) and response regulator (RR). Arabidopsis have 5 genes each coding HPt factor (AHP) and 22 genes each coding RR (ARR). ARRs form a gene family that includes the type-A and type-B. Thus, a multistep AHK2/3/4->AHP->ARR phosphorelay(s) was considered to be involved in a siglaling network in response to cytokinin.
In this study, we focused on a set of type-A ARRs and characterized their overexpressors and T-DNA insertion mutants. We also examined their expression patterns and intracellular localization in detail. These results will be discussed with special reference to cytokinin signal trunsduction and His-Asp phosphorelay network.
