An Arabidopsis protein that interacts with the cytokinin‐inducible response regulator, ARR4, implicated in the His‐Asp phosphorylay signal transduction

Previously, Arabidopsis thaliana was shown to possess a set of response regulators (ARR-series), which are implicated in the prokaryotic type of signal transduction mechanism, generally referred to as the His-Asp phosphorylay. Among them, ARR4 is a typical phospho-accepting response regulator, whose expression was recently demonstrated to be rapidly induced by a cytokinin-treatment of the plant. To gain insight into the presumed His-Asp phosphotransfer signaling mechanism as well as the role of ARR4 in this higher plant, in this study we adopt the widely used yeast two-hybrid system, and report the identification of an Arabidopsis protein that has an ability to interact physically with the cytokinin-inducible ARR4 response regulator.