Abstract
RSG is a bZIP transcription activator modulating endogenous gibberellins (GA) level. One of interacting proteins with RSG is 14-3-3 protein, which regulates the intracellular localization of RSG. The 14-3-3 protein binds to targets by recognizng phosphoserine residues and regulates these functions. We reported that Ser114 of RSG is essential for association with 14-3-3 proteins and that CDPK is involved in phosphorylation of Ser114 (2004 Annual Meeting of JSPP).
To investigate in vivo interaction between CDPK and RSG, we adopted agroinfiltration to introduce agrobinaryplasmids into Nicotiana benthamiana for transient expression. GST-RSG expressed was precipitated from leaf extracts by anti-GST antibody and kinase activity in the immuno-precipitates was analysed by in-gel kinase assay using recombinant GST-RSG. CDPK phosphorylating Ser114 of RSG was detected in the immuno-precipitates of GST-RSG. The results suggest that CDPK interacts to RSG in vivo. Furthermore, CDPK associates with 14-3-3 proteins as phosphorylated RSG.
