Abstract
RSG is a bZIP transcriptional activator, which regulates shoot growth by controlling GA level. Suppression of RSG resulted in severe dwarfism. We have demonstrated 1) RSG interacts with 14-3-3 proteins, which are broadly conserved regulatory factors in eukaryotes, through phosphorylated serine-114(PS114) in RSG; 2) Binding with 14-3-3 inhibits the transport of RSG to nucleus; 3) RSG is not statically sequestered in the cytoplasm by 14-3-3, but dynamically shuttling between nucleus and cytoplasm; 4) endogenous level of GA regulates function of RSG by control of intracellular localization; 5) GA promotes nuclear export of RSG by 14-3-3 binding of RSG through phosphorylation of S114 of RSG. We identified CDPK as an RSG kinase that specifically phosphorylates S114 of RSG. Then, commitment of CDPK to the GA-induced cytoplasmic migration of RSG was examined. Furthermore, we examined the effects of over-expressing of CDPK on the feedback regulation of GA biosynthetic genes.
