Abstract
In Arabidopsis thaliana, Histidine-to-Aspartate (His->Asp) phosphorelay is a paradigm of signaling system that is considered to be involved in response to plant hormones, including ethylene and cytokinin. In the current framework of His->Asp phosphorelay (AHK->AHP->ARR) in this higher plant, the AHP (histidine-contianing phosphotransfer) family members appear to act as regulatory intermediates of signal transduction. Although A. thaliana has 5 AHP members (AHP1 to AHP5), no information is available with regard to their biological functions. As the main objective of this study, we extensively characterized all of 5 AHPs, through searching for proteins that interact with AHPs, constructing a series of transgenic plants carrying each promoter::GUS fusion genes. Furthermore, we constructed a set of transgenic plants, aberrantly expressing each AHP. These results from such intensive analyses with regard to properties of AHPs are discussed with special reference to the His->Asp phosphorelay signal transduction network.
