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, through phosphorylated serine-114 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 localization of RSG.
It is known that disappearance of DELLA protein, such as RGA, from the nucleus by protein degradation upon GA stimuli triggers GA responses in the cell. We examine whether the similar mechanism works in the case of RSG. After GA stimuli, protein levels of RSG and mutant RSG which can not bind to 14-3-3 are not changed. Consequently, GA regulates RSG mainly by controlling intercellular localization of RSG through binding with 14-3-3.
